Machete

The Machete is a close combat weapon introduced in Left 4 Dead 2.

Like all other melee weapons, uses the slot of the Pistol. It can slice and decapitate common Infected. All melee weapons have an identical range. It's practically neck-and-neck with the Frying Pan for the best hits-over-time (excluding the Chainsaw), but uses less hit-boxes resulting in less hits. As a bladed weapon, the more kills you get with it, the more blood you get splashed on your screen and on your weapon.

It can also do heavy damage to Special Infected if not killing them outright, although this isn't recommended unless they have ensnared or pinned another survivor, since some Special Infected can attack you before you can kill them or are too far way to do anything with a melee weapon, and the other Special Infected have abilities and effects that make them too dangerous to consider killing with a melee attack.

Trivia

 * Survivors bring their other hand up while holding the machete in the same way the Sniper from Team Fortress 2 does with his Kukri.
 * Another interesting note is that the community of Team Fortress 2 commonly debates whether to call the Sniper's weapon a kukri or a machete.

Exernal Links
Machete gameplay