The United States Small Business Administration was established on July 30, 1953 when Congress passed the Small Business Act. The stated purpose of the SBA is to help small businesses remain viable in the United States. The SBA helps small businesses increase their borrowing power by directly granting loans and also guaranteeing loans that banks and other lenders make to small businesses.
The SBA guarantess five different loan products:
Learn more about the SBA Loan process from the government's official SBA site.
This article from Entreprenuer Magazine is a good overview of some of the SBA's loan programs.
One final concise article on SBA loans from the folks at Small business Notes.com.