 In addition, some systems will do "page turns" using a foot pedal, which means that the performer does not have to miss playing music during a page turn, as often occurs with paper parts.Of special practical interest for the general public is the Mutopia project, an effort to create a library of public domain sheet music, comparable to Project Gutenberg's library of public domain books.The International Music Score Library Project (IMSLP) is also attempting to create a virtual library containing all public domain musical scores, as well as scores from composers who are willing to share their music with the world free of charge.