What does it mean that Redis operations are atomic?

Redis is single-threaded for command processing — it executes one command at a time, in order, with no concurrent interleaving. This means every Redis command is inherently atomic: either it fully executes or it doesn't; no two commands can execute simultaneously and interfere with each other's state. This makes Redis ideal for implementing distributed counters, rate limiters, and locks. For example, INCR atomically reads a value, increments it, and writes it back — in any other system this read-modify-write would require a lock to prevent race conditions. Lua scripts and MULTI/EXEC transactions extend this atomicity to groups of commands that must execute without interruption.