Comment 1 for bug 1274734

Ubuntu 12.04 LTS (precise) is supported for five years, and Ubuntu 12.10 (quantal) for 18 months. Both releases remain within their support periods. But since Ubuntu 13.04 (raring), non-LTS support has been reduced to nine months, so raring counter-intuitively EOLed three months before quantal will.

https://wiki.ubuntu.com/Releases lists the current status of each release, including release and EOL dates. Subscribe to https://lists.ubuntu.com/mailman/listinfo/ubuntu-announce for notifications of releases and EOLs.