Why is MySQL used so often in web development?

Question

I have often wondered why MySQL has become so popular. Any ideas why? Are there specific reasons behind its success? (Please keep answers analytical)

Answer 1

1. It is free, which means it sees more use on personal projects as well as on hosting platforms that provide a DMBS solution.
2. It is one of the few solutions that can run on almost any operating system.
3. It uses basic SQL rather than a specialized variant, meaning that it requires less-specialized knowledge to use.
4. Setup and configuration is more straight-forward and less time-consuming than most other options.