edx.org Edx.org

   
Build new skills. Advance your career. | edX

Domain Summary

What is the traffic rank for Edx.org?

• Edx.org ranks #11,166 globally on HypeStat.

What percent of global Internet users visit Edx.org?

0.0103753% of global Internet users visit Edx.org

How many people visit Edx.org each day?

• Edx.org receives approximately 511.5K visitors and 3,394,915 page impressions per day.

Which countries does Edx.org receive most of its visitors from?

• Edx.org is mostly visited by people located in United States,India,United Kingdom.

How much Edx.org can earn?

• Edx.org should earn about $13,143.68/day from advertising revenue.

What is Edx.org estimated value?

• Estimated value of Edx.org is $15,134,609.73.

What IP addresses does Edx.org resolve to?

• Edx.org resolves to the IP addresses 13.32.208.69.

Where are Edx.org servers located in?

• Edx.org has servers located in Seattle, Washington, 98109, United States.

edx.org Profile

Title:Build new skills. Advance your career. | edX
Description:Discover thousands of offerings — from free courses to full degrees — delivered by world-class partners like Harvard, Google, Amazon and more.
Tags:
Category:Science and Education / Education
About: Free courses designed specifically for interactive study via the web, provided by MIT, Harvard and Berkeley. edX will also research how students learn and how technology can transform learning, both on-campus and worldwide.
EdX offers free online courses and classes. Find the latest MOOC from the world’s best universities including MIT, Harvard, Berkeley, UT and others. Topics include business, computer science, finance, history, literature, math, science, statistics and more. Edit Site Info

What technologies does edx.org use?

These are the technologies used at edx.org. edx.org has a total of 10 technologies installed in 10 different categories.

edx.org Traffic Analysis

Edx.org is ranked #11,166 in the world. This website is viewed by an estimated 511.5K visitors daily, generating a total of 3.4M pageviews. This equates to about 15.5M monthly visitors. Edx.org traffic has increased by 1.95% compared to last month.
Daily Visitors511.5K
4.21%
Monthly Visits15.5M
1.95%
Pages per Visit6.64
0.19%
Visit duration06:39
17.96%
Bounce Rate39.19%
7.08%
Is this your site?Verify your site's metrics.
Daily Unique Visitors:
511,495
Monthly Visits:
15,498,299
Pages per Visit:
6.64
Daily Pageviews:
3,394,915
Avg. visit duration:
06:39
Bounce rate:
39.19%
Global Reach:
0.0103753%
Monthly Visits (SEMrush):
15,474,072
Monthly Unique Visitors (SEMrush):
6,631,969
Monthly Visits (SimilarWeb):
15,043,964
HypeRank:
11,166
SEMrush Rank:
7,541
SimilarWeb Rank:
3,161
*All traffic values are estimates only.

Traffic sources

Direct:
73.00%
Referral:
10.24%
Search:
13.42%
Social:
2.80%
Paid:
0.55%

Desktop vs Mobile

Desktop:
49.69%
Mobile:
50.31%

Total Visits Last 3 Months

13.7M
JUN
15.2M
JUL
15.5M
AUG

Visitors by country

Country
Users%
 
United States 20.09%
 
India 6.43%
 
United Kingdom 4.05%
 
Mexico 3.30%
 
Canada 3.11%

Where do visitors go on edx.org?

 
Reach%Pageviews%PerUser
edx.org
68.37%30.30%2.32
learning.edx.org
47.84%45.93%5.0
courses.edx.org
36.41%14.25%2.0
authn.edx.org
23.54%5.88%1.3
support.edx.org
2.28%0.65%1.5
Last update was 208 days ago
     
This can take up to 60 seconds. Please wait...

*HypeStat.com is not promoting or affiliated with edx.org in any way. Only publicly available statistics data are displayed.

Search Engine Indexes

Search engine indexes are huge databases or collections of net pages that search engines like google like google and yahoo use to retrieve applicable facts while customers carry out searches. These indexes are created through search engines like google and yahoo through crawling and indexing net pages from throughout the internet.
Google Index:
71,000
Bing Index:
4,050
Baidu Index:
140,000

Moz Data

Domain Authority (DA) is a metric developed by Moz. DA is a score that predicts the ranking potential of a website on search engine result pages (SERPs). Moz calculates Domain Authority on a logarithmic scale from 1 to 100, with higher scores indicating a greater likelihood of ranking well in search results. Moz Domain Authority of edx.org is 89.
Domain Authority:
  89
Page Authority:
  63
MozRank:
  6

 

SEMrush is a complete on line advertising and marketing platform that gives a extensive variety of gear and functions to help companies and entrepreneurs in enhancing their on line visibility and optimizing their virtual advertising and marketing strategies.
SemRushSemRush
Domain:
  edx.org
Rank:
(Rank based on keywords, cost and organic traffic)
  7,541
Organic Keywords:
(Number of keywords in top 20 Google SERP)
  388,484
Organic Traffic:
(Number of visitors coming from top 20 search results)
  329,765
Organic Cost:
((How much need to spend if get same number of visitors from Google Adwords)
  $1,077,000.00

Revenue report

Google.com would generate approximately $13.1K per day if the source of income were advertisements, which equates to an estimated monthly revenue of $394.3K and annual gross revenue of approximately $4.8M. Based on these figures, the site's net worth is estimated at around $15.1M.

How much would edx.org make?

Daily Revenue:
$13,143.68
Monthly Revenue:
$394,310.40
Yearly Revenue:
$4,797,443.20
*All earnings values are estimates only.

Daily earning by country

 
CountryPageviewsEarning
 
United States 681,980$3,293.96
 
Canada 105,500$637.22
 
United Kingdom 137,515$368.54
 
India 218,422$83.00
 
Mexico 111,883$31.33

Loss of money due to Adblock?

Daily Revenue Loss:
$837.24
Monthly Revenue Loss:
$25,117.31
Yearly Revenue Loss:
$305,593.91
Daily Pageviews Blocked:
242,361
Monthly Pageviews Blocked:
7,270,840
Yearly Pageviews Blocked:
88,461,884

Daily revenue loss by country

 
CountryBlockedLost Money
 
United States 122,756$592.91
 
Canada 26,375$159.30
 
United Kingdom 22,002$58.97
 
India 61,158$23.24
 
Mexico 10,070$2.82

How much is edx.org worth?

Website Value:
$15.1M

Ad Experience Report

Summary of the ad experience rating of a website for a specific platform.

Mobile summary

Root domain:
edx.org
Ad filtering:
(Chrome is not filtering ads on your site.)
Off
Status:
(The status of the site that is reviewed for the Better Ads Standards.)
Not reviewed

Desktop summary

Root domain:
edx.org
Ad filtering:
(Chrome is not filtering ads on your site.)
Off
Status:
(The status of the site that is reviewed for the Better Ads Standards.)
Not reviewed

Abusive Experience Report

Summary of the abusive experience rating of a website.
Root domain:
edx.org
Enforcement:
(Chrome is not preventing your site from opening new windows or tabs.)
Off
Status:
(The status of the site reviewed for the abusive experiences.)
Not reviewed

Where is edx.org hosted?

Edx.org may be hosted in multiple data centers distributed in different locations around the world. This is probably just one of them.
Server IP:
13.32.208.69
ASN:
AS16509 
ISP:
Amazon.com, Inc. 
Server Location:
Seattle
Washington, WA
98109
United States, US
 

Other sites hosted on 13.32.208.69

There are no other sites hosted on this IP

How fast does edx.org load?

The average loading time of edx.org is 438 ms. The Desktop speed index is 82 and mobile speed index is 29.
Average Load Time:
438 ms

Page Speed (Google PageSpeed Insights) - Desktop

82
0-49 50-89 90-100 i

Field Data

Over the last 30 days, the field data shows that this page has a SLOW speed compared to other pages in the Chrome User Experience Report.We are showing the 90th percentile of FCP and the 95th percentile of FID.

First Contentful Paint (FCP)3.4s 51% of loads for this page have a fast (<1s) First Contentful Paint (FCP) 51% 32% of loads for this page have an average (1s ~ 2.5s) First Contentful Paint (FCP) 32% 15% of loads for this page have a slow (>2.5s) First Contentful Paint (FCP) 15%
First Input Delay (FID)54ms 94% of loads for this page have a fast (<50ms) First Input Delay (FID) 94% 3% of loads for this page have an average (50ms ~ 250ms) First Input Delay (FID) 3% 1% of loads for this page have a slow (>250ms) First Input Delay (FID) 1%

Origin Data

All pages served from this origin have an SLOW speed compared to other pages in the Chrome User Experience Report. over the last 30 days.To view suggestions tailored to each page, analyze individual page URLs.

First Contentful Paint (FCP)3.0s 47% of loads for this page have a fast (<1s) First Contentful Paint (FCP) 47% 38% of loads for this page have an average (1s ~ 2.5s) First Contentful Paint (FCP) 38% 14% of loads for this page have a slow (>2.5s) First Contentful Paint (FCP) 14%
First Input Delay (FID)32ms 96% of loads for this page have a fast (<50ms) First Input Delay (FID) 96% 2% of loads for this page have an average 50ms ~ 250ms) First Input Delay (FID) 2% 1% of loads for this page have a slow (>250ms) First Input Delay (FID) 1%

Lab Data

Max Potential First Input Delay 130 ms
The maximum potential First Input Delay that your users could experience is the duration, in milliseconds, of the longest task. Learn more
Time to Interactive 2.7 s
Time to interactive is the amount of time it takes for the page to become fully interactive. Learn more
Estimated Input Latency 20 ms
Estimated Input Latency is an estimate of how long your app takes to respond to user input, in milliseconds, during the busiest 5s window of page load. If your latency is higher than 50 ms, users may perceive your app as laggy. Learn more
Total Blocking Time 160 ms
Sum of all time periods between FCP and Time to Interactive, when task length exceeded 50ms, expressed in milliseconds.
Speed Index 1.7 s
Speed Index shows how quickly the contents of a page are visibly populated. Learn more
First CPU Idle 2.3 s
First CPU Idle marks the first time at which the page's main thread is quiet enough to handle input. Learn more
First Contentful Paint 1.0 s
First Contentful Paint marks the time at which the first text or image is painted. Learn more
Performance budget  
Keep the quantity and size of network requests under the targets set by the provided performance budget. Learn more
First Meaningful Paint 1.6 s
First Meaningful Paint measures when the primary content of a page is visible. Learn more

Page Speed (Google PageSpeed Insights) - Mobile

29
0-49 50-89 90-100 i

Field Data

Over the last 30 days, the field data shows that this page has a AVERAGE speed compared to other pages in the Chrome User Experience Report.We are showing the 90th percentile of FCP and the 95th percentile of FID.

First Contentful Paint (FCP)2.8s 51% of loads for this page have a fast (<1s) First Contentful Paint (FCP) 31% 46% of loads for this page have an average (1s ~ 3s) First Contentful Paint (FCP) 46% 22% of loads for this page have a slow (>3s) First Contentful Paint (FCP) 22%
First Input Delay (FID)140ms 93% of loads for this page have a fast (<100ms) First Input Delay (FID) 93% 5% of loads for this page have an average (100ms ~ 300ms) First Input Delay (FID) 5% 1% of loads for this page have a slow (>300ms) First Input Delay (FID) 1%

Origin Data

All pages served from this origin have an AVERAGE speed compared to other pages in the Chrome User Experience Report. over the last 30 days.To view suggestions tailored to each page, analyze individual page URLs.

First Contentful Paint (FCP)2.6s 31% of loads for this page have a fast (<1s) First Contentful Paint (FCP) 31% 48% of loads for this page have an average (1s ~ 3s) First Contentful Paint (FCP) 48% 20% of loads for this page have a slow (>3s) First Contentful Paint (FCP) 20%
First Input Delay (FID)177ms 96% of loads for this page have a fast (<100ms) First Input Delay (FID) 92% 5% of loads for this page have an average 100ms ~ 300ms) First Input Delay (FID) 5% 2% of loads for this page have a slow (>300ms) First Input Delay (FID) 2%

Lab Data

Time to Interactive 14.7 s
Time to interactive is the amount of time it takes for the page to become fully interactive. Learn more
Estimated Input Latency 70 ms
Estimated Input Latency is an estimate of how long your app takes to respond to user input, in milliseconds, during the busiest 5s window of page load. If your latency is higher than 50 ms, users may perceive your app as laggy. Learn more
First Contentful Paint (3G) 7470 ms
First Contentful Paint 3G marks the time at which the first text or image is painted while on a 3G network. Learn more
Total Blocking Time 1,630 ms
Sum of all time periods between FCP and Time to Interactive, when task length exceeded 50ms, expressed in milliseconds.
Speed Index 6.3 s
Speed Index shows how quickly the contents of a page are visibly populated. Learn more
First CPU Idle 10.5 s
First CPU Idle marks the first time at which the page's main thread is quiet enough to handle input. . Learn more
First Contentful Paint 3.7 s
First Contentful Paint marks the time at which the first text or image is painted. Learn more
Performance budget  
Keep the quantity and size of network requests under the targets set by the provided performance budget. Learn more
First Meaningful Paint 6.6 s
First Meaningful Paint measures when the primary content of a page is visible. Learn more
Max Potential First Input Delay 550 ms
The maximum potential First Input Delay that your users could experience is the duration, in milliseconds, of the longest task. Learn more

Does edx.org use compression?

Website compression is the process of reducing the size of website files, such as HTML, CSS, JavaScript, and image files, to improve website performance and load times. Compressing website files can significantly reduce the amount of data that needs to be transferred from the server to the user's browser, resulting in faster page load times and improved user experience. Files on edx.org are reduced by 83%.
edx.org use gzip compression.
Original size: 814.95 KB
Compressed size: 136.43 KB
File reduced by: 678.52 KB (83%)

Google Safe Browsing

Google Safe Browsing is a service provided by Google that helps protect users from visiting websites that may contain malicious or harmful content, such as malware, phishing attempts, or deceptive software.
This site is not currently listed as suspicious

MyWot.com Reputation Ratings

MyWOT (short for "My Web of Trust") is a web-based reputation and rating service that provides users with information about the trustworthiness and safety of websites. edx.org has 94 Safety Reputations.
Status:
  SAFE
Safety Reputations:
  94
Safety Confidence:
  47
Child Safety Reputations:
  94
Child Safety Confidence:
  47

SSL Checker - SSL Certificate Verify

An SSL (Secure Sockets Layer) certificate is a digital certificate that establishes a secure encrypted connection between a web server and a user's web browser. It provides authentication and encryption, ensuring that data transmitted between the server and the browser remains private and protected. edx.org supports HTTPS.
 edx.org supports HTTPS
     
Verifying SSL Support. Please wait...
Common Name: sni.cloudflaressl.com
Organization: "Cloudflare, Inc."
Location: San Francisco, California, US
Issuer: Cloudflare Inc ECC CA-3
Valid from: May 14 00:00:00 2023 GMT
Valid until: May 13 23:59:59 2024 GMT
Authority: CA:FALSE
Keysize:
Common Name: Cloudflare Inc ECC CA-3
Organization: "Cloudflare, Inc."
Location: US
Issuer: Baltimore CyberTrust Root
Valid from: Jan 27 12:48:08 2020 GMT
Valid until: Dec 31 23:59:59 2024 GMT
Authority: CA:TRUE
Keysize:

Verify HTTP/2 Support

HTTP/2 (Hypertext Transfer Protocol version 2) is a major revision of the HTTP protocol, which is the foundation of data communication on the World Wide Web. It was developed as an improvement over the previous HTTP/1.1 version to enhance web performance and efficiency.
 edx.org supports HTTP/2
     
Verifying HTTP/2.0 Support. Please wait...

Site Categories

Website categories are used to classify websites based on their content or purpose. These categories provide a way to organize and filter websites, allowing users to find relevant information or ensure compliance with specific regulations or policies.
Online Courses/E-learning Portals

Http Header

HTTP headers are extra portions of records despatched among a consumer (which include an internet browser) and a server at some stage in an HTTP request or response. They offer instructions, metadata, or manipulate parameters for the conversation among the consumer and server.
content-length: 0
location: https://www.edx.org/
date: Fri, 29 Sep 2023 10:48:11 GMT
server: AmazonS3
x-cache: Hit from cloudfront
via: 1.1 063f496e2a2a07219bf3fbec39d54de4.cloudfront.net (CloudFront)
x-amz-cf-pop: IAD66-C1
x-amz-cf-id: lNHIcWOse9LTqrqQhdrbgnjZ__he_9vL5Ldb3Xdd_3VKApt8TmTAtQ==
age: 39845

HTTP/2 200 
date: Fri, 29 Sep 2023 21:52:15 GMT
content-type: text/html
cf-ray: 80e773c1dde01404-ORD
cf-cache-status: DYNAMIC
cache-control: public, max-age=1800
last-modified: Fri, 29 Sep 2023 17:17:24 GMT
set-cookie: prod-edx-cf-loc=US; Domain=edx.org; Path=/; Expires=Sun, 29 Sep 2024 21:52:15 GMT
strict-transport-security: max-age=2592000
vary: Accept-Encoding
x-amz-id-2: 2gzqCSi4tF5M8YFsi/yhAIYco9/RP8pO4SxwB9IWHV0AdJ8nOE714Kan9pe1qhLf44Ptv2OwOMw=
x-amz-request-id: 14Y8M3CZ6DD6WCJ2
x-frame-options: DENY
x-nginx-cache-status: HIT
server: cloudflare
content-encoding: gzip

DNS Lookup

DNS entries (Domain Name System) are a critical component of the Internet infrastructure. They act as directories that translate human-readable domain names (such as example.com) to machine-readable IP addresses. DNS records are stored on DNS servers and help forward internet traffic efficiently.
Type Ip Target/Txt TTL
CAA letsencrypt.org 30
CAA digicert.com 30
CAA amazon.com 30
CAA comodoca.com 30
TXT atlassian-domain-verification=xpq-aB5aXpxCKMr7r3eDPHyz+H8uPB16jIppdmlCIloVrhEtCrKucpx/Nnqr1xJg 30
TXT google-site-verification=VmJhKMomzXGRq96pOMWst3QD0KvnurTNsPHNhv8qt1k 30
TXT atlassian-sending-domain-verification=5c0c6ccf-f137-44f4-8b59-90f8c09ba730 30
TXT MS=ms89770774 30
TXT segment-site-verification=2ZGPEbxZ025BzXh516qCWeQ7sGFFltDx 30
TXT smartsheet-site-validation=bxOSD4ibPoym5apZEnln5bh2ckPn2Z1M 30
TXT dropbox-domain-verification=9dvz1ju53nbf 30
TXT adobe-idp-site-verification=3f2215d19f499a970c4305a59755a6a1eb0f9850d7777a297a46db1e644e71c7 30
TXT apple-domain-verification=6VfkC2MXgvez6NHJ 30
TXT facebook-domain-verification=h2gg5zwnyax0dj0jyo4aafdtkpiiyu 30
TXT docusign=0a19ada1-ffcb-427c-a276-7d9b7cc7e911 30
TXT miro-verification=5e1d5616af42e7df86ea6b4831af8c0217d01193 30
TXT google-site-verification=S98FBFJqeURQhHxBtC_UG84orCIkl7msuarSO5NoIPc 30
TXT v=spf1 include:_spf.google.com include:mail.zendesk.com include:servers.mcsv.net include:aspmx.sailthru.com include:spf.cphosts.net include:_spf.atlassian.net -all 30
TXT amazonses:0rz9BauM6+L1fwnDKUmS4nofo+8gZvTReGo5q/EliHY= 30
TXT google-site-verification=3wMRITKQ9E2388ON5mfWt98s48OBDMVzPO-7xY3U6H4 30
TXT adobe-idp-site-verification=0614d0e44da9d4b72a75d19e9138eb0052991fb2acb9d62cfd048eee75c7f24b 30
TXT atlassian-domain-verification=HN7ngRpg8qAazURti1cdbKGDap2uVfm7uvUYF/m9UkSHtwZM2P5Ub6muuhN47h1w 30
TXT google-site-verification=-_Eevdy8NShzLkex28P2wC3zjbfVweCs0k5z5f6gm_k 30
TXT google-site-verification=tVFyMKACOBTnEVoW-XJ0jbunNP7bDxPLxUZpGs9j9go 30
MX alt2.aspmx.l.google.com 30
MX aspmx2.googlemail.com 30
MX aspmx3.googlemail.com 30
MX alt1.aspmx.l.google.com 30
MX aspmx.l.google.com 30
SOA 900
Mname ns-73.awsdns-09.com
Rname awsdns-hostmaster.amazon.com
Serial Number 1
Refresh 7200
Retry 900
Expire 1209600
Minimum TTL 300
A 13.32.208.79 60
A 13.32.208.121 60
A 13.32.208.2 60
A 13.32.208.69 60
NS ns-1753.awsdns-27.co.uk 3524
NS ns-828.awsdns-39.net 3524
NS ns-73.awsdns-09.com 3524
NS ns-1472.awsdns-56.org 3524

Whois Lookup

Domain WHOIS is a public database that provides information about domain names, including registered owners, contact information, domain registrars, registration and expiration dates, name servers, and other relevant information. Domain registration for this website began on November 25, 2001 and will expire on November 25, 2023 if not renewed. This website is now assigned through the registrar Gandi SAS. The WHOIS data for this website's domain was last updated on October 30, 2022.
Domain Created:
2001-11-25
Domain Expires:
2023-11-25
Domain Updated:
2022-10-30
Domain Age:
22 years 4 months 29 days
Domain Registrar:
Gandi SAS
Domain Owner:
edX
WhoIs:
 

Domain Name: edx.org
Registry Domain ID: 976f399549454c9fbb4c5f5fe36b329c-LROR
Registrar WHOIS Server: http://whois.gandi.net
Registrar URL: http://www.gandi.net
Updated Date: 2022-10-30T16:13:32Z
Creation Date: 2001-11-25T19:02:08Z
Registry Expiry Date: 2023-11-25T19:02:08Z
Registrar: Gandi SAS
Registrar IANA ID: 81
Registrar Abuse Contact Email: email
Registrar Abuse Contact Phone: +33.170377661
Domain Status: clientTransferProhibited https://icann.org/epp#clientTransferProhibited
Registry Registrant ID: REDACTED FOR PRIVACY
Registrant Name: REDACTED FOR PRIVACY
Registrant Organization: edX
Registrant Street: REDACTED FOR PRIVACY
Registrant City: REDACTED FOR PRIVACY
Registrant State/Province: MA
Registrant Postal Code: REDACTED FOR PRIVACY
Registrant Country: US
Registrant Phone: REDACTED FOR PRIVACY
Registrant Phone Ext: REDACTED FOR PRIVACY
Registrant Fax: REDACTED FOR PRIVACY
Registrant Fax Ext: REDACTED FOR PRIVACY
Registrant Email: Please query the RDDS service of the Registrar of Record identified in this output for information on how to contact the Registrant, Admin, or Tech contact of the queried domain name.
Registry Admin ID: REDACTED FOR PRIVACY
Admin Name: REDACTED FOR PRIVACY
Admin Organization: REDACTED FOR PRIVACY
Admin Street: REDACTED FOR PRIVACY
Admin City: REDACTED FOR PRIVACY
Admin State/Province: REDACTED FOR PRIVACY
Admin Postal Code: REDACTED FOR PRIVACY
Admin Country: REDACTED FOR PRIVACY
Admin Phone: REDACTED FOR PRIVACY
Admin Phone Ext: REDACTED FOR PRIVACY
Admin Fax: REDACTED FOR PRIVACY
Admin Fax Ext: REDACTED FOR PRIVACY
Admin Email: Please query the RDDS service of the Registrar of Record identified in this output for information on how to contact the Registrant, Admin, or Tech contact of the queried domain name.
Registry Tech ID: REDACTED FOR PRIVACY
Tech Name: REDACTED FOR PRIVACY
Tech Organization: REDACTED FOR PRIVACY
Tech Street: REDACTED FOR PRIVACY
Tech City: REDACTED FOR PRIVACY
Tech State/Province: REDACTED FOR PRIVACY
Tech Postal Code: REDACTED FOR PRIVACY
Tech Country: REDACTED FOR PRIVACY
Tech Phone: REDACTED FOR PRIVACY
Tech Phone Ext: REDACTED FOR PRIVACY
Tech Fax: REDACTED FOR PRIVACY
Tech Fax Ext: REDACTED FOR PRIVACY
Tech Email: Please query the RDDS service of the Registrar of Record identified in this output for information on how to contact the Registrant, Admin, or Tech contact of the queried domain name.
Name Server: ns-1472.awsdns-56.org
Name Server: ns-1753.awsdns-27.co.uk
Name Server: ns-73.awsdns-09.com
Name Server: ns-828.awsdns-39.net
DNSSEC: unsigned
URL of the ICANN Whois Inaccuracy Complaint Form: https://www.icann.org/wicf/
>>> Last update of WHOIS database: 2023-09-29T21:53:31Z