IMSLP, also known as the International Music Score Library Project or Petrucci Music Library, was started in 2006. The logo on the main page is a capital letter A. It was taken from the beginning of the very first printed book of music, the Harmonice Musices Odhecaton. It was published in Venice in 1501 by Ottaviano Petrucci, the library's namesake.
The IMSLP/Petrucci Music Library is currently owned and run by Project Petrucci LLC.