Whether you're a professional artist, or a collector looking towards the future, archival-quality framing is the best way to preserve and display your artwork. Acid-free materials, such as 100% rag mat board and alpha mats, are necessary to stabilize works on paper in a frame. They should back the work, as well as be in front, as the visible mat. Acid-free foamboard or acid-free cardboard should be used in addition the the mat "sandwich."
Regular matboard, which is a cheaper material, turns color with age, and can actually spray acid from its core onto the paper it is next to.
What is the guiding principle of archival, or conservation framing? It is that nothing be done to the work that would cause it to deteriorate, and that anything done in the framing of it is reversible.
The other great enemy of works that are framed is light. The paradox is that light allows one to see the art, but light will also destroy it. Ultraviolet-filtering glazing is a must in conservation of artworks, photos, documents, etc. There are multiple kinds of coated glass and acrylics that offer 98-99 percent protection from UV rays.