redpen

v. A technique in digital art instruction, usually informally. When an artist submits a digital work in progress for critique, other artists will save a copy of it to their own computers and draw in notes or corrections in bright red (most artists will sketch in black or blue) for the original artist to use as a guideline in further developing the piece. However, because it's considered criticism and most art critics are assholes, doing this without the invitation of the original artist is considered rude and presumptuous by artists and a generous boon by art critics.