Language | Libraries | Comparison
To use an existing library in a sketch simply go to the Sketch menu, choose "Import Library", and pick from the libraries available. This will insert an #include statement at the top of the sketch for each header (.h) file in the library's folder and make the library's functions and constants available to your sketch.
Because libraries are uploaded to the board with your sketch, they increase the amount of space used by the ATmega8 on the board. If a sketch no longer needs a library, simply delete its #include statements from the top of your code.
These are the "official" libraries that are included in the Arduino distribution.
These libraries are compatible Wiring versions, and the links below point to the (excellent) Wiring documentation.
These are not (yet) included with the Arduino distribution and may change.
Corrections, suggestions, and new documentation should be posted to the Forum.