The besom, or broom, is perhaps the most recognized tool of the witch. The broom is so highly connected to witches and witchcraft that many people would be surprised to realize that the besom is considered a secondary tool of the witch and that many modern witches do not possess one. Traditionally, besoms were composed of birch twigs secured to a wooden stick or pole. Today, any broom may be used in magic, as long as it is properly consecrated, though modern witches due tend to like the visual aesthetics of the old-fashioned besoms vs. the store bought and modern variety.
In the folklore surrounding witches, the broom was the vehicle of flight for witches travelling by air to the sabbat, though other items were often used as well. The broom also had a secondary role as a substitute for the witch. In this role, a witch wishing to attend a sabbat would place a broom in bed next to her sleeping husband and by magic make the husband believe the broom was herself. Of course in these situations it is believed the witch was able to travel to the sabbat by some other means.
The actual truth concerning the origins of the witch's broom can be found in folk magic. Additionally, it should be noted that like the cauldron, brooms were a prized possession of a family and were usually hand-made. As such, it is quite understanding that so much lore grew up around such an important tool of a household.
Brooms have a long history and use in folk magic, usually in rites for cleansing, banishing, protection, fertility, and even for black magic purposes. For example, a broom lain down in a doorway will protect against those who wish you will as one's enemies will not step over it. To make an unwanted guest leave, call out that persons name, turn a broom upside down and tap it's handle on the floor three times, lean it up against the back door, still upside down, and then sprinkle salt on the bristles. To banish a person and prevent them from returning, throw salt & pepper on the ground behind them when they leave and quickly sweep it out and off the porch, and preferably into the street, while cursing them and telling them never to return. To make a sick person die, "sweep" a broom through the air over them as they sleep. This will sweep away their life-force. Additionally, in the 1800s a fertility ritual enacted by newly married African-American couples whereby the couple would jump over a broom was quite popular. This ritual was said to bless the union and to help ensure many strong, healthy offspring.
In the book, Witches by Erica Jong, Jong provides an interesting observation of how the broom, a symbol of female oppression, has been transformed into a symbol of freedom with regard to the belief in the witches' flight. Ironically, male witches were believed to often fly upon pitchforks. The seemingly lack of surviving folklore on male witches and pitchforks seems to emphasize just how firmly connected the practice of witchcraft is with "the fairer sex".
For modern Wiccans, the besom is primarily used as a tool for cleansing, either personal in nature or of the cleansing of the sacred circle. Some Wiccans have also borrowed the ritual of broom jumping during their wedding ceremonies known as hand-fastings. As with all tools of the witch, non-witches should not touch the besom. If a non-witch touches a besom then the besom will need to be cleansed and re-blessed before being used again in ritual.