Here are the philosophy and goals of the site:
We at the IMSLP believe that music should be something that is easily accessible for everyone. To this end, we have created the IMSLP in order to provide music scores free of charge to anyone who has internet access. IMSLP will always be freely accessible.
The ultimate goal of the IMSLP is to gather all public domain music scores, in addition to the music scores of all contemporary composers who wish to release them to the public free of charge. However, another main goal of IMSLP is to facilitate the exchange of musical ideas outside of compositions: for example, the analysis of a particular piece of music. We hope to build a growing community of dedicated musicians and music lovers, who can use this site as a platform for enjoying music.
Music costs so much to buy and I'm thinking I will have great fun looking for new music to play in this new database.