The rook chess pieces can be a powerful piece because of the number of spaces it can access at any one time. You get two of them at the beginning but don't waste them.
The rook chess piece is limited to horizontal and vertical straight line movement for as many free spaces as it wishes. However, unlike bishop, the rook can potentially access every square on the board. Since this piece can access all 64 spaces it may generally be considered more powerful then a knight or bishop.
Depending on where the rook is located on the board it's movement is limited anywhere from 0-7 spaces in any vertical or horizontal direction
assuming that the board is empty. If the piece is in the middle of
the board, for example, it can only move 3 or 4 spaces depending on
the direction. On the other hand, if it's in the corner then it can
only move in two directions up to 7.
The rook is commonly found in many end game scenarios. It is probably the most frequently found piece in end game scenarios. This may be because the rook is many times most powerful after other pieces have been removed from the board. After a board is empty it gives the rook the freedom to move for long distances.
Chess pieces can come in many styles so the rook will look different from set to set. Staunton style is the one most people are probably familiar with since this is the tournament standard.