A blocker is a player on the special teams similar to a lineman on offense or defense. Blockers specialize in blocking opposing players from breaking through the line to tackle the kicker.
Blocking in football requires blockers to run into each other with force and prevent other players from getting forward progress. Blockers will use their hands to push opposing players.
Tackling is the act of grabbing and pushing another player to the ground. Tackling the ball carrier is an important job of the blocker.
Holding is penalty in football that is given to a player that holds on to an opposing player preventing their movement. Holding results in a loss of 10 yards. Blockers must be careful not to grab onto the jersey of an opposing player or they risk getting called for holding.