Mendeley Reference Manager also allows you to organize your citation library, using collections, tags, and other designations.
You can create collections to organize your documents in whatever groupings make sense to you. Documents can be in more than one collection.
To create a new collection, click on the "New Collection" field under "Collections" and begin typing. Once you have created a collection, you can rename it or delete it by right clicking on the collection name in the left hand panel or by clicking on the three dots which appear at the end of the collection name when hovering your mouse over the name.
To add a reference to a collection, drag and drop it onto a collection in the left hand panel, or select multiple references and select "Add to Collection" from the "Organize" menu at the bottom of the screen.
Tags may sometimes be automatically generated when you pull citations from online, especially when pulling from articles with keywords from journal databases. You can add additional tags that help you arrange your documents around concepts that make the most sense to you, and use the "Filters" option in the top righthand corner of the Reference Manager to view specific tags.
Mark documents using the star to indicate your favorite sources. They will automatically be added to your "Favorites" folder.