When you get a really good print, the chances are you'll want to show it off. The traditional way is to mat it for framing. Matting a print sandwiches it between two sheets of matboard, one of them with a bevelled window through which the print shows.
Matting and framing a print is like creating a multi-layer sandwich with all of the layers shown here.
To mat a print, you start with a sheet of matboard for the overmat and a mounting board for the backing. Matboard is often made up of three layers: the colored face paper, the core and the backing and comes in a variety of thicknesses (specified as 2-ply, 4-ply and so on), colors, and textures. The best material for valued prints is acid-free archival or museum quality matboard that won't eventually discolor a print. For short-term display or less valuable prints, ordinary matboard is less expensive and widely available in art and framing supply stores. Both pieces of board should be the same size but you can use different thicknesses—4-ply for the mounting board and 2- ply for the overmat. The thicker mounting board will keep the sandwich more rigid and protect the print from creasing.
After trimming the matboard to the desired size, you use a mat cutter to cut a beveled window into the overmat. Matboard usually has a white core so when beveled, the image is set off by a white line. This overmat not only protects and shows off the image, it also prevents the surface of a framed print from coming in contact with the glass to which it might eventually stick.
Here are details of how the mat and mounting board can be hinged to keep them aligned (left) and how tape can be used to create a "T" mount to mount the print on the mounting board (right).
Once the window is cut, you hinge the two sheets together with tape and then position the print so it's aligned with the window in the overmat. One way to then attach the print to the mounting board is with photo corners that are hidden when the overmat is lowered. This avoids having adhesives in direct contact with your photo and also makes it easy to remove the print. Another way is to make tape hinges using acid-free linen tape available where good quality matboard is sold. You should avoid dry mounting which uses heat, and materials such as cellulose tape, masking tape, brown paper tape, or cheap glues. Tapes and glues are considered archival only if they don't affect the print's color over time and are completely removable.