Automatic Properties

When I open my obsidian vault, it automatically creates the properties “cssclasses”, “tags” and “aliases”.

I keep these properties but they keep showing up. is there a reason for that?

I can understand the tags properties but don’t know what I’m supposed to do with cssclasses and aliases :confused:

Obsidian comes with a set of default properties:

tags - Tags.
aliases - Aliases.
cssclasses - Allows you to style individual notes using CSS snippets.