Windows 7 was released on July 22,2009. It's had a great run, but all good things must come to an end. Microsoft has announced that it will stop supporting Windows 7 after January 14, 2020. That means that Microsoft will no longer be issuing security fixes for Windows 7, leaving you more vulnerable to virus attacks. If you don't care about the added risk, you can go ahead and keep using Windows 7. But if you have files on your computer that you don't want to risk losing (e.g. pictures, documents, music), use your computer in a business setting or do things like online banking, you should really consider upgrading to Windows 10. For people with older PCs, the best thing to do is probably to get a new PC with Windows 10 pre-installed. For newer PCs, it might make sense to upgrade them to Windows 10 directly. But every situation is different, so contact me if you want help determining which option is right for you.
Here is an article that goes into more detail about the whole situation.