As new and better technologies enter the marketplace, another batch of products near the end of their lifecycles. You shouldn’t be surprised when any of your business’s technology has reached end-of-support—your Company’s CIO or IT outsourcing provider should have already consulted with you and developed a plan for upgrades and replacements. Continued use of end-of-life technology can expose your business to several risks—such as extended downtime, cybersecurity holes, lack of product support, and issues with 3rd party application functionality—which may cause trouble for your Company.

End-of-life or end-of-support (specifically, end of mainstream support) products are hardware and software that have reached the end of their useful life and are no longer marketed, sold, or supported by their manufacturer. The availability of new technology is the primary reason products reach the end of their lifecycles. However, other factors like market changes also determine the length of a product's lifecycle. As hardware and software age, manufacturers stop providing security patches and no longer roll out new features for those products. Businesses, to mitigate security concerns, should upgrade their end-of-life products as soon as possible.

Support can be cost-prohibitive beyond Microsoft's extended support period and only delays the inevitable. Therefore, when products exit extended support, paid custom support contracts (if offered) are the only option. Updates to the product, including security updates, should not be expected outside the paid custom support contract terms.

Mainstream support and extended support define the amount of time Microsoft gives for its Windows operating systems – essentially, expiration dates.

When your computer’s operating system is within the mainstream support period, it means Microsoft is still taking care of that version. By taking care, we mean providing security updates for any bugs that emerge, releasing design changes and warranty claims, for example.

Microsoft usually ends mainstream support five years after the operating system's release, which then pushes it into extended support. This period usually runs for another five years too, but you get less support. Essentially it means the Company stops adding new features and ends complementary support for that [particular] version. But it still provides bug fixes and patches.

This support model applies to Microsoft's business, developer, and desktop operating system products.

Source: http://home.bt.com/tech-gadgets/computing/what-is-the-difference-between-windows-mainstream-support-and-extended-support-11364050710601

Go here to see a table outlining the support phases for the Business, Developer, and Desktop Operating System Policy.

Source: https://support.microsoft.com/en-us/help/17140/lifecycle-faq-general-policy-questions

https://support.microsoft.com/en-us/lifecycle/search

Microsoft site showing SQL lifecycle

https://support.microsoft.com/en-us/lifecycle/search/1044

If Microsoft releases a Service Pack, mainstream support will extend by two years.