SOE assumes you don't know what armor is.

SWG has a special feature on armor up at their site.

Brave explorers and adventurers of the galaxy are bound to get into a scrape or two along the way. Several types of durable and dependable armor are out there to take the brunt of the dents and scratches so you don't have to. Learn how to best protect yourself against the dangers of the galaxy as we explore the facts about armor.

Take a look at the official Star Wars Galaxies site.