Final answer:
Mats are primarily used to protect artwork by acting as a spacer between the art and the glass of the frame. They also help in displaying the artwork by creating an attractive border around it.
Step-by-step explanation:
The primary purpose of a mat in framing is to protect the artwork. Mats serve as a spacer between the art and the glass of the frame, which can prevent any potential damage caused by the artwork touching the glass. This is especially important for photographs or delicate prints which could stick to the glass and get ruined. Moreover, mats also aid in displaying artwork by providing an aesthetically pleasing border that highlights the piece and can enhance the overall look of the framed artwork.