IMSLP stands for the International Music Score Library Project and was started in 2006. (http://imslp.org/wiki/IMSLP:About) "The ultimate goal of the IMSLP is to gather all public domain music scores, in addition to the music scores of all contemporary composers (or their estates) 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." (http://imslp.org/wiki/IMSLP:Goals)