Libraries are categories of blocks that can be imported in any Snap! project. They are written in Snap! and as a result function like custom blocks.
In order to use libraries, one has to import them from File > Libraries > [name of the library]. Information about what the library does can be found out by reading the description, which is located under the list of blocks in the library.
The following is a list of libraries available in Snap! as of version 9.1.1:
The following libraries are available in version 10.0:
EDC libraries:
There are also user-made libraries which can be imported into projects from File > Import. Some of them are:
List of media found in Media Libraries
Snap! also includes a few small media libraries. To access these you can go to File > Costumes / Backgrounds / Sounds. There are 539 images in the Costumes library, 12 images in the Backgrounds library, and 12[1] sounds in the Sounds library.