In Star Trek, a pattern buffer stores a person's pattern during transporter materialization or dematerialization.
The transporter converts matter into an energy pattern, transmits that pattern, and reconstructs the subject at the destination. The pattern buffer temporarily holds the information during this process and can also retain patterns for a limited time when transport cannot be completed immediately.
The pattern buffer is not the transporter pad, which is the platform where a subject stands, nor is it the Heisenberg compensator, a fictional component associated with resolving quantum-mechanical transport problems. The transporter chiefly moves people and objects by converting and reconstructing their matter rather than physically carrying them through space.
Transporter technology appears throughout the Star Trek franchise, although its exact operation and limitations vary between series and films. Episodes sometimes use stored patterns to restore people, duplicate them, or create unusual transport effects.