- Substitution core
- One player leaves the court, another enters in the same spot, during a dead ball before the serve. Each costs one of the team's limited subs per set.
- Starter role
- A player listed on the lineup at the start of the set, occupying one of the six rotation positions.
- Substitute role
- A player who enters from the bench to replace someone on court.
- Locked sub pair key rule
- When starter A is replaced by sub B, the two become bound for the rest of the set. Only A can re-enter for B; B can only ever leave for A. This pairing is the backbone of every in-match sub decision — Lesson 0001.
- Re-entry key rule
- A starter who was subbed out may return — but only into the same rotation position they left, and only for the same substitute who replaced them.
- Rotation position core
- One of the six spots on court (front: 4-3-2, back: 5-6-1). Subs are about who fills a spot, not which spot rotates — the spot stays put.
- Libero role
- A back-row defensive specialist who swaps in for a back-row player without using a substitution. Cannot attack above net height or rotate to the front row. Libero swaps are unlimited and tracked separately — covered in a later lesson.
- Defensive specialist (DS) role
- A back-row defender who enters via a normal substitution (unlike the libero). Counts against the sub limit and follows the locked-pair rule.
- Serving substitution tactic
- Subbing a stronger server in for a player when their spot rotates to serve, then often subbing back. A common use of the locked pair.
- Sub limit key rule
- The cap on team substitutions per set (libero swaps excluded). The number depends on ruleset and changes across cycles — always check the current USAV rulebook. Running out = players can get "stuck" on or off court.
- Stuck (out of subs) situation
- When the sub limit is spent, on-court players must finish the set and benched starters can't return. Knowing your remaining count prevents nasty surprises.