Every reference in your library can be edited.  This is useful if you need to make corrections or add information such as project names or course numbers.

References may contain incorrect data from the database - it is important to make the corrections in your Library.

Organization: 

Organize your library in a way that fits your style.  You can use one library "all my references" and keyword search to find items on different topics.  If folders are a better method, you can make different folders and move references into these as needed. 

Sharing:

One of the handy features of EndNote is the ability to share different folders with colleagues.  As long as someone has an EndNote account you can give them read or read-write access to a collection or folder.  A colleagues with read-write access can upload and edit references in the library.