The Engineer is a close-range combat and sabotage specialist. His main weapon is a compact and quick SMG. The Engineer must keep away from open spaces to avoid Sniper's bullets.
The Engineer is also very skillful with explosives and can plant or defuse bombs faster than other players. His mines are motion-triggered and deal a whole lot of damage and can kill an enemy not wearing protective gear. And finally, Engineers can restore both their own and their teammates' armor.