Terran's are the humans of the Starcraft world. They are the 2nd most mechanical unit out of the three main races. Most of their forces consist of mechanical units. Their weapons usually consist of regular guns, to bombs, to on road vehicles and air vehicles.
Terran's are the most vulnerable of the three races, not having anything but armor to help them resist Zerg and Protoss attacks. However, Terran's have access to the most power weapons on the game which include everything from Siege Tank's to Nuclear Bomb's. They also have other good vehicles like the Goliath's and the Vulture's. They have a powerful air force as well. Wraith's are their main air attack force which can cloak themselves so they can attack the enemy undetected. The Terrans are pretty weak when it comes to defense and such, being beings of flesh, but they had upgrade their armor, so that does take off most of the damage that hurts them. However, they are best at taking out flying enemies and enemies long ranged. Marines are the base of the Terrans and can hit long ranged, close ranged, and flying enemies.
The Terrans focus more on the mechanical side of their race due to their weak bodies. The armor they wear can be upgraded along with the weapons, and the armor and weapons of the machines can be upgraded to a high level. Terrans use bullets and missles for their main attack force. Marines use machine guns to attack, and Goliaths use missles to take out air forces. However, Wraith's can use lasers to attack ground units. Firebats use flamethrowers as a weapon in close range combat against ground units, and Battlecrusiers use lasers against all types of units/structures.
 Terran Units
There are many types of Terran units, such as;
Related ThreadsStarCraft II Terran Units Details Revealed - last post by LinkinPork @ Aug 30, 2007
[Theory] Terran Infantry - last post by @ May 23, 2008
Terran Strategy Discussion - last post by @ Jan 23, 2011
Terran Suck On Island Maps - last post by @ May 12, 2008
Defense For Terran - last post by @ Jan 30, 2003