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. Buttons are one of the oldest and most widely used types of fastener, consisting of a disk, ball, or dome-shaped fastener attached to one piece of fabric and joined to another piece of fabric by being drawn through a hole or loop. Their use can be dated from the Bronze Age, and they arose in the Middle East, China, and Rome.
Buttons were first primarily used for ornamentation. They became important in late Medieval/early Renaissance Europe when they were brought back from the Crusades, at which point they were available in materials such as silver, ivory, bone, and mother-of-pearl, but clothes fastenings were still primarily laces or hooks. When buttonholes were invented in the Renaissance, buttons became functional, and 1830-1850 is considered the Golden Age of Buttons. Today, people can also find ones made of glass, stone, horn, leather, papier-mache, ceramic, Bakelite, wood, plastic, and polymer clay. There is also a more recent kind of button that serves a very particular need: shirt collar expander buttons widen a tight shirt collar by creating a bridge between the fastener and the hole that is concealed behind a necktie.
There are two basic types of buton, depending on how they are attached to a piece of material. Sew-through ones have holes in them, often two or four, and thread is passed through the holes and the material to bind the button in place, either using a sewing machine with a special foot or by hand. Shaft buttons have a connector on the back that is attached to the material with thread.
Shaft buttons offer a variety of interesting opportunities for decoration. They may be covered in fabric over a base called a ring or covered in leather placed over a base called a form. Another kind of button is actually an elaborate knot made of cord or braid, sometimes called a Chinese ball button.
Both button loops and holes may be found singly and in sets. Loops extend beyond the edge of the fabric, while buttonholes are cut in the fabric itself. There are three standard shapes of holes: rectangular, oval, and keyhole; and they may be bound or overcast. Bound ones are created by adding extra fabric to the area and are often found in tailored garments. Overcast buttonholes, made by machine or by hand, use stitching to keep the cut edge of fabric around the area from unraveling. Usually, there is an exact match of the number of holes and the number of buttons, but shirt cuffs often feature several holes so the wearer can choose the one that gives the best fit.
The dimension given for a button's size is its diameter. In general sewing instructions for US sewers, on store-bought sewing patterns for example, the number and size needed is specified by inches in the notions section. People should be aware, however, that the international standard for measurement is called the ligne and there are 40 English ligne in an inch. Sewers will often find ligne listed along with inches and/or millimeters when shopping for notions outside the US.
Buttonhole size is determined, of course, by the size of the buttons. The basic formula states that the length of the hole should equal the diameter of the button plus its height, with an extra 1/8 inch added for an overcast buttonhole.