There are actually two different sites to the best help. There's that list of features and a comprehensive explanation of how to use them, of course.

The other side though is sometimes even more important it's what this thing does as a high-level introduction so you can understand all the things you're supposed to be able to do depending on the software this is some sometimes not obvious and that explanation can be really helpful to understand all the things you're supposed to be able to do and thus plan to use all those features.