An EndNote library can store unlimited number of references.
You can share your library with others by creating a compressed filename.enlx file:
File > Compressed Library (.enlx) > Create
Filename.enlx includes the filename.enl file as well as its associated .Data folder.
What is an EndNote library?
It is an EndNote file. When you create a file in MS Word, it is called word document, and in MS Excel, spreadsheet. In EndNote, when you create a file, it is called "library".
Create a new library: