The Astrophysics Data System (ADS) provides access to the astronomical literature. It is funded by NASA and hosted at the Harvard- Smithsonian Center for Astrophysics. It consists of two main parts. The abstract service allows you to search the tables of contents and abstracts of essentially the whole astronomical literature. The article service contains the scanned full articles of a large part of the astronomical literature. Access to the ADS is free to anybody world-wide.