On April 14th mainstream support for Windows XP will end. for the next 5 years the operating system goes into extended support. The table below illustrates the differences between mainstream and extended support.
The Microsoft Windows XP product page explains it as following:
Mainstream Support delivers complimentary and paid support, free security updates, and bug fixes to all Windows customers who purchase a retail copy of Windows XP (i.e., a shrink-wrapped, not pre-installed copy). Mainstream Support for Windows XP will continue through April 2009.
Extended Support delivers free security updates to all Windows customers. Customers can also pay for support on a per incident basis. Extended Support for Windows XP will continue until April 2014. New bug fixes require the Extended Hotfix Support program.