Understanding Apple Music Collections in iTunes

Hi I like my iTunes and my Music player on the phone.

So when adding new music to playlists is great though take a bit of time...

• Everyone on youtube and blogger seems to jump over the Collections part.. What is it and how do I edit it?

I have playlists on the top, then artists, albums, songs, different types of Music (that apple is really is not good at), and then "collections" before compozers and that is downloaded.

Everything seems to be well with how I edit the music in iTunes except that Collections part, there are very few songs and I dont really see what I am going to use it for.

[Re-Titled by Moderator]