The Microsoft support lifecycle policy has been around since October 2002 but still seems to be a source of confusion for many.  In effect, there are three phases of support:

• Mainstream support provides full product support, including security updates, hotfixes and the ability to raise product enhancement requests.
• Extended support means that a product is on its way towards retirement and, in order to open a support case on a products in its extended support phase, a Premier Support contract with Microsoft is required. There is a higher risk involved in relying on products in their extended support phase (when compared with mainstream support products) as extended support is only available for business and developer products – and it does not allow product enhancement requests, or non-security updates (unless an Extended Hotfix Support Agreement is available – more on that in a moment…).
• Self-help means “Google it!” as Microsoft will not accept support requests for products in this phase.  The Microsoft knowledge base is available, as are all the resources of the Internet, but the risks involved with of running out-of-support products is high.

For business and developer products, there is normally 5 years of mainstream support, followed by 5 years of extended support.  Self-help via the Microsoft online support site will be available for at least 10 years.  There are some exceptions (e.g. Windows XP) as these products predate the support lifecycle policy.  For consumer products there is no extended support, just 5 years of mainstream support, and the commitment to self-help from Microsoft is 8 years.

Microsoft does have support solutions for individual customers that are forced to stray outside mainstream support.  Extended Hotfix Support agreements allow customers to request non-security hotfixes for products in their extended support phase and these agreements involve substantial fees (for the agreement, and for every non-security hotfix requested). Furthermore, there is no contractual commitment from Microsoft to agree to a hotfix request. Custom Support agreements are prohibitively expensive and designed to provide limited support during the self-help
support phase. These agreements are product- and customer-specific.

Finally, be aware that the support lifecycle does not just apply to product versions, but service pack and cumulative update versions too.