Quick question re custom class

Can someone clarify for me when I should be putting scripts into the Assets > Standard Assets > Scripts folder, and when I can just have them in the Assets folder, when creating new classes? Is it just when using static functions which won't be instanced?

Any script can be put anywhere in the Assets folder (though, for organizational sake, I would advise keeping them in a "Scripts" folder or something similar). There are cases where the folder matters, and they're covered pretty completely here. If that doesn't cover what you're looking for, please post a follow-up!