Hello everyone, Ive been reading up on a poker book by Phill Hellmuth, and he keeps using the term "three bet" and "three bet" and Im having trouble understanding what this means.

For example Say you are playing $1/2 Limit and the Big Blind is at $1 and small Blind is at .50. Player "A" Calls, Player "B" Bets $1, Player "C" Raises $1..... Is this a three bet or a tow bet? Does the Original $1 Blind Count as bet 1 making Players "B" bet a "two bet" and Players "C" bet a 'three bet" ?