Collage is an artistic technique that involves gluing different materials like paper, photos, or objects onto a surface to create an original composition. The document provides instructions for making a musical collage using materials like colored paper, crepe paper, and magazine clippings glued onto cardboard. The instructions guide the reader to draw a pentagram and musical note, cut and arrange paper rectangles within the pentagram, and add musical notes made of circles and sticks. Once dry, the completed collage can be displayed on a wall.