Felt is a textile that is produced by matting, condensing, and pressing fibers together. Felt can be made of natural fibers such as wool or animal fur, or from synthetic fibers such as petroleum-based acrylic or acrylonitrile or wood pulp–based rayon. Blended fibers are also common. Natural fiber felt has special properties that allow it to be used for a wide variety of purposes. It is "fire-retardant and self-extinguishing; it dampens vibration and absorbs sound; and it can hold large amounts of fluid without feeling wet..."

Felt from wool is one of the oldest known textiles. Many cultures have legends about the origin of felt-making. The story of Saint Clement and Saint Christopher states that the men packed their sandals with wool to prevent blisters while fleeing from persecution. At the end of their journey, the movement and sweat had turned the wool into felt socks.

Most likely, felt's origin was in east Asia, where there is evidence of feltmaking in Siberia (Altai mountains) in Northern Mongolia, and there is more recent evidence that dates back to the first century CE in Mongolia. Siberian tombs (7th to 2nd century BCE) show the broad uses of felt in that culture, including clothing, jewelry, wall-hangings, and elaborate horse blankets.^{[failed verification]} Employing careful color use, stitching, and other techniques, these feltmakers were able to use felt as an illustrative and decorative medium upon which they could depict abstract designs and realistic scenes with great skill. Over time, these makers became known for the beautiful abstract patterns they used, which were derived from plant, animal, and other symbolic designs.

From Siberia and Mongolia, feltmaking spread across the areas that were held by the Turkic-Mongolian tribes. Sheep and camel herds were central to the wealth and lifestyle of these tribes, both of which animals were critical to producing the fibers that were needed for felting. For nomads who travelled frequently and lived on fairly treeless plains, felt provided housing (yurts, tents, etc.), insulation, floor-coverings, and inside walling, as well as many household necessities from bedding and coverings to clothing. In the case of nomadic peoples, an area where feltmaking was particularly visible was in trappings for their animals and for travel. Felt was often featured in the blankets that went under saddles.

Dyes provided rich coloring, and colored slices of pre-felts (semi-felted sheets that could be cut in decorative ways) along with dyed yarns and threads were combined to create beautiful designs on the wool backgrounds. Felt was even used to create totems and amulets that had protective functions. In traditional societies, the patterns embedded in the felt were also imbued with significant religious and symbolic meaning.

Feltmaking is still practised by nomadic peoples, such as Mongols and Turkic people) in Central Asia, where rugs, tents, and clothing are regularly made. Some of these are traditional items, such as the classic yurt, or ger, while others are designed for the tourist market, such as decorated slippers. In the Western world, felt is widely used as a medium for expression in both textile art and contemporary art and design, where it has significance as an ecologically responsible textile and building material.

In addition to Central Asian traditions of felting, Scandinavian countries have also supported feltmaking, particularly for clothing.

In the wet felting process, hot water is applied to layers of animal hairs, while repeated agitation and compression causes the fibers to hook together or weave together into a single piece of fabric. Wrapping the properly arranged fiber in a sturdy, textured material, such as a bamboo mat or burlap, will speed up the felting process. The felted material may be finished by fulling.