Tool
The include libraries tool gives easy access to an online library. When a library is included it is treated like a "built-in" library in the file.
Including libraries is very useful when you need to reference a library multiple times in one file. Normally, to reference something in a library, you open a formula and type Library.LibrayName.etc.etc. When a library is included, the "Library.LibraryName." portion isn't necessary.