The Digital Public Library of America (DPLA) is a platform for sharing unique resources amongst the nation's libraries. Most of these resources come from the Special Collections of the contributing institutions, meaning they are unpublished, one-of-a-kind, primary source materials (wondering what primary source is?).
You are welcome to use any and all of these resources, but DO pay attention to the RIGHTS information listed underneath each resource. The rights information will tell you WHAT you can do with the resource.
DPLA welcomes software developers, creative thinkers, and others to create apps to share data available in DPLA. There are some cool apps in their App Library!