Cut and plug is used for small areas of carpet that are burned, stained or similarly damaged. The damaged piece of carpet is cut out and a good piece of matching carpet is hot glued into its place. If leftover matching carpet isn't available, a small piece is usually taken from a closet or similar hidden location.

Restretching is used for loose and wrinkled carpets. Like a facelift, restretching makes carpets tight again. It prolongs the carpet's life by eliminating wrinkles which can cause the carpet to wear more quickly from the constant back and forth bending that occurs when it is stepped on. It also reduces the danger of tripping on the loose material. Seam repair is needed when an existing seam has come undone. Often a strip containing the seam is cut out and hot glued back in place.

-- Tips courtesy of HomeAdvisor.com