Fasteners are used to create permanent and semi-permanent bonds between materials, as well as joints that can be opened and closed, and purely decorative additions. The early advent of the snap is not clearly recorded, but the initial version of what came to be the snap seems to have been used on European theatre costumes to facilitate quick changes in the 1840s. These were next used widely on long ladies gloves, which were in vogue in the later nineteenth century. Although early designs had issues with both rust and reliability, by the 1890s there were many different brands, and the "ball and socket" shape that we know today had emerged. They were popularized as a quick, easy alternative to hook-and-eye fasteners and buttons, although they had less holding power, and the four major types we know today emerged.
Basic snaps are small circular fasteners that have a ball side and a socket side. When applying by hand, each side is sewn using four holes to one side of the fabric, which can then be joined together when fastened. These are available in metal, plastic, and nylon, and are sized fine to heavy.
Covered snaps can be bought ready to apply or can be created by a crafter. The covers are generally fabric, and the completed fasteners are attached to the garment by sewing. Covered snaps can also be used as embellishment. If you affix the socket side to the outside of a garment or other item, you can then use the ball sides with their decorative covers to change the ornamentation of the item, by your choice of cover size, color, style, and so on.
No-sew snaps are similar in appearance to buttons and are affixed to fabric by cleats rather than by sewing. Pearl snaps, introduced into Western clothing in the 1940's as a safeguard to reduce injuries and damage when clothing got snagged on the trail, are in this category, and were intended to resemble mother-of-pearl buttons. There are a variety of manufacturers of no-sew fasteners, which require either a hammer or a commercial tool for application. These fasteners may be sized by inches, millimeters, or by a sizing system of even numbers, with 3/8" being called 14 and 5/8" being called 24.
Snap tape features fasteners affixed to fabric tape. You sew a strip of the tape with the socket side to the fabric's under layer, and the other strip of tape that contains the ball sides to the over layer. This kind of tape is very popular in casual wear and clothing for young children; one often finds it in infant sleepers and onesies.