A few of them are layers, filters, and plugins created by their enthusiastic community. What you find are handy photo editing functions. There’s no need to use advanced software when all your image requires is a crop.
But it’s still a great photo editing tool for minor changes. Although the name sounds like Microsoft Paint, it is a dedicated photo editor. Not only is it free, but it’s also quick and easy to operate. The best free photo editor software is often the simplest.