Ticks are small, insect-like creatures that live in woods and fields. They attach to you as you brush past bushes, plants, and grass. Once on you, ticks often move to a warm, moist location, like the armpits, groin, and hair. At that point they typically attach firmly to your skin and begin to draw blood.
Ticks can be fairly large -- about the size of a pencil eraser -- or so small that they are almost impossible to see. Ticks can cause a variety of health conditions ranging from harmless to serious.
See also: Tick bites