Although traditional collages are made from magazines and bits of torn paper, unpredictable materials add interest and depth to a collage. Tactile surfaces like cloth, furs, leaves, vinyl, plastics, coins, strings and other items may be used. Usually a collage is glued to a paper or a board. These items may be glued down with student-grade glue or archival-quality acid free adhesive. A collage may even be sewn to a canvas, or made as a quilt, which is another form of collage. Alternatively, a collage may be rendered digitally using software such as Photoshop. This type of collage may exist only electronically, or it may be printed to photo paper at a later time.
Balance, in whatever form, is one of the most important elements of two-dimensional design. Regardless of whether or not you're making a collage, balance is crucial for the success and visual impact of any two-dimensional piece. Balance itself may take many forms within one image. Balance is achieved through the distribution of color, structure and layout. There should be a connection between the various pieces of the collage. There should be symmetry or asymmetry, a color scheme (whether monochromatic or complimentary or inclusive of all colors, or some other plan), and a reason for each choice.
A collage may serve any number of functions--it may be a piece of fine art, a decoration for a billboard, a sign or an insert in a scrap book. A collage may be made of different images placed together, meant to work in tandem with each other, or the various elements of a collage may be cut up and placed together to form a completely separate image that is not dependent on the materials it is made from in order to convey meaning.