A multi-tool (or multitool) is any one of a range of portable, versatile hand tools that combines several individual functions in a single unit. The smallest are credit-card or key sized units designed for carrying in a wallet or on a keyring, but others are designed to be carried in a trouser pocket or belt-mounted pouch.
The idea of incorporating several tools in one small portable unit is very old, dating back at least as far as Middle Roman times. Many of these were based around eating.
Among the earliest contemporary examples is the Swiss Army knife as supplied by makers Victorinox and Wenger. The actual version supplied to the Swiss army includes a knife blade, a reamer, a bottle-opener–screwdriver–wire stripper, and a can-opener–screwdriver. Besides Victorinox and Wenger, many other manufacturers now make similar knives.
Other versions may include items like a nail file, tweezers, folding scissors, a tooth pick, a magnifying glass, screwdriver bits and others. There are also versions that have special tools for specific sports or outdoor activities like golf, horseback riding, hunting or fishing. Versions intended for cyclists may have a selection of allen (hex) keys, a selection of wrenches, screwdrivers, a spoke key, and a chain-breaker.