Hunter trap

A hunter trap is a trap that Survival hunters can set on the ground. A trap produces a damaging or slowing effect to enemies who come within its range. The ability to set traps is exclusive to hunters.

Tactics
A trap skill allows you to set a trap on the ground which will exist for 1 minute, and will activate when a mob comes within range, performing their designated function. Since patch 2.0.1, traps can be placed while in combat. Place a trap and lead a monster back into it to set it off. This becomes easier with your ranged weapon.

Players now need to be wary of relying on traps against higher level mobs. Traps have been resistible since patch 1.6 (according to Blizzard, this has always been intended). When they are resisted they just either disappear without notice or sometimes Freezing Traps will break early. The resist rate is relatively high versus higher level mobs.

Traps
Traps are placed together in a pullout button, similar to the Call Pet and mage teleports/portals.
 * Freezing Trap - A trap that freezes the first enemy that approaches, preventing all action for a 1 Minute (8 seconds in PvP). Any damage caused will break the ice.
 * Ice Trap - A trap that creates an ice slick around itself for 30 sec when the first enemy approaches it. All enemies within 10 yards will be slowed by 60% while in the area of effect.
 * Snake Trap - A trap that replaces Ice Trap, but with a similar effect using snakes to attack the first enemy to approach.
 * Explosive Trap - A trap that explodes when an enemy approaches, causing Fire damage and leaves additional Fire damage over 20 sec to all affected targets within 10 yards as a DoT. (Damage depends on your Attack Power)

Trap Launcher
As of patch 4.0.1, hunters can now use a Trap Launcher to lay traps up to 40 yards away at a cost of 20 focus. This ability will allow the hunter to use traps as a ranged-attack method and throw traps on mobs and bosses without having to enter melee range. Hunters can reduce the focus cost of Trap Launcher by 10 with the Glyph of Trap Launcher.

Since Mists of Pandaria, the Trap Launcher longer needs to be activated each time the hunter wants to shoot a trap, instead the launcher acts as an active buff, similar to the Aspects. While active, all traps used have the target ring to shoot them at the specific location, while inactive, the traps are placed at the hunter's feet. The focus cost has also been removed.

Uses
Freezing Trap is a great trap to use while taming. Activate the trap at the very edge of the targeted beast's aggro range and then taunt it to attack, having to cross the trap to do so. The mob will be frozen in place and you will have a precious few more seconds to focus and tame the beast.

A well placed freezing trap can save your main healer and by extension the group, or can crowd control one extra mob during a pull. Laying an explosive trap, feigning death and laying another is a great way to take down a big group of mobs, who might be attacking in numbers. A fire trap is another nice damage dealer and during PvP battles (particularly in the Battlegrounds) an ice trap can be the thing that turns a battle. The best hunters are the ones who know how to use their traps, know which one to use in a particular situation, where to place a trap to maximize damage and/or crowd control, and how know to lay double and sometimes triple traps. All of these skills take experience and practice, and this, along with superior pet control, differentiates an average hunter from a great one.