Every bicyclist knows the importance of handlebars. Without handlebars, you have no control of the bike. You do everything from the handlebars: steer, shift, and even brake. Lightweight handlebars reduce the overall weight of the bike, making it easier to ride and steer.
Carbon fibre is particularly popular for its combination of light weight and strength. Many handlebars are adjustable, at least in height, to provide more control when riding. Keep both hands on the handlebars.