Jammer
The jammers are the only skaters who can score points.  After a jammer's first pass through the pack, she scores a point for each opposing team member she passes.  If either jammer completes her first pass through the pack legally passing each opposing pivot or blocker, the first jammer to do so is the Lead Jammer.  The jammers are identified by the stars on their helmets.

Pivot
The pivots set the pace for the pack and are the last lines of defense for their teams.  They are responsible for calling out plays on a moment's notice, and all skaters look to this position for guidance.  The pivots are identified by the stripes on their helmets.

Blocker
Each team has 2 middle blockers and 1 lead blocker.  Blockers and pivots try to stop the opposing team's jammer.  Blockers may also knock down the opposing team's blockers and pivot to assist their own jammer through the pack.

Team
There are a maximum of 20 skaters on a team, 14 skaters on the roster for a bout, and 5 skaters on the track or in the penalty box at a time.

Bout
2 teams Bout in 2 30-minute periods.  Each period is made up of several 2 minute (or less) jams.

Jam
A jam is a scoring session that can last up to 2 minutes.  If a Lead Jammer is declared, the Lead Jammer may call off the jam at any time prior to the 2 minute time limit by placing her hands on her hips.  If no Lead Jammer is declared, the jam runs the full 2 minutes.  The teams have up to 30 seconds between jams to form up for the next jam.

Whistles
1 long whistle starts the pack
2 short whistles start the jammers
2 shorts whistles signal lead jammer
1 long whistle signals a major penalty
4 short whistles call off the jam

Pack
The pack is the largest group of pivots and blockers, containing members of both teams, skating in proximity (within 10 feet of the nearest pack skater).  A "split pack" is two groups of pivots and blockers, equal in number, separated by more than 10 feet.  If the pack is split, no legal pack is defined and no points can be scored by a passing jammer.  If the pack becomes split, the referees will instruct the skaters to reform the pack, issuing penalties to skaters unable to do so.

In Play
A pivot or blocker is in-play if they are in bounds and not more than 20 feet in front of or behind the pack.  Pivots and blockers who are not in play may not assist or block any other player.  A player who has moved out of play must take the opposite action to move back in play -- catch up if fallen behind, fall back if sprinted ahead, and move back in bounds if out.  In bounds jammers are always allowed to block each other, regardless of how far ahead of or behind the pack they are.