Where can I find the status of the released versions of Ubuntu?

I want to know where I can find updated information about all the stable and in-development versions of Ubuntu, where I can find this information?

This question is meant to be a canonical question. It expects to answer the following questions:

• Is X version stable yet?
• Is X version in beta?
• Is X version still supported?
• What versions are still supported?
• What are the versions in Beta/Alpha?
• Until where X version will be supported?
• Have X version ceased support?
• When will be X version released?
• Where I can download any release?
• When will the next LTS version of Ubuntu be released?

The list is not exhaustive.

Supported Releases

The currently supported releases will always be in the Wiki page of Ubuntu at:

https://wiki.ubuntu.com/ReleaseTeam#Releases.Current

This includes the current point release, Long Term Support release and regular releases.

Future (in development) Releases

For future (beta/alpha) versions of Ubuntu you may check:

https://wiki.ubuntu.com/ReleaseTeam#Releases.Future

Older (EOL) Releases

To know the supported dates of older (EOL) releases, you may visit:

https://wiki.ubuntu.com/ReleaseTeam#Releases.End_of_Life

All releases can be downloaded at http://releases.ubuntu.com, for older releases you may look at http://old-releases.ubuntu.com.

The release schedule of any version will be at https://wiki.ubuntu.com/<codename>/ReleaseSchedule, replacing <codename> with the codename for that release, e.g. for Trusty Tahr:

https://wiki.ubuntu.com/TrustyTahr/ReleaseSchedule

Over at Wikipedia they keep this useful graph: