Toe jam is a slang reference to the dead skin cells, sock fluff, surface dirt, sweat, skin oils and bacteria which tend to collect between a person's toes throughout the day. Poor hygienic practices or certain feet-related medical conditions such as athlete's foot can make the appearance and odor of foot jam even more noticeable.
There's really no practical way to avoid some accumulation of dead skin cells, skin oils or bacteria between one's toes, since all of these are organic in nature. In the same way that sweat, bacteria and skin oils can build up in the underarm area and cause body odor, a similar combination can cause toe jam to form between toes. Daily washing and scrubbing can reduce the severity and recurrence of buildup, but it would be impossible to stop dead skin cells or sweat from collecting between the toes.
Some have compared the odor of toe jam to a pungent form of cheese, which may be the result of gases released by the odor-causing bacteria. Sock lint can also be attracted to the skin oils and sweat which build up whenever the foot is contained in a shoe for hours at a time. Dirt contained in shoes or deposited on shower floors can also become trapped between the toes. As long as a shoe or sock covers the foot, the generated body odor is relatively contained, but exposure of toe jam to the outside world can be unpleasant.
Toe jam itself is not considered a medical condition, although it could be indicative of other serious foot-related ailments such as athlete's foot and other fungal infections. It is generally addressed by foot baths, professional pedicures, foot deodorants or medicated foot sprays. Wearing clean cotton socks and well-ventilated shoes should also help reduce the hostile foot environment which contributes to the build up. Wearing clean shower shoes or flip-flops in communal showers should also help minimize odors and potential infections.