Trap is subtype of item in Shadow Era.

Traps are currently limited to the Hunter class.
Traps are a special kind of item that are played face-down in the support row (so opponent can not read the card), and activate when a specific action written on the particular trap occurs.
In Call of the Crystals, there were only two different traps (Net Trap and Death Trap), and they both had different casting costs, so it was actually possible to tell which had been played despite that they were face-down.
In following sets, more traps have been introduced, so it is harder to determine the trap that has been set this way.
After being activated, whatever the effect is resolved or not, the trap is destroyed and goes to its owner's graveyard.