From SC2Pod
APM (Actions Per Minute) is a measure of activity level typically used in RTS e-sports. Specifically, it measures the average number of mouse clicks and keyboard key presses per minute for the duration of the match. A higher APM typically indicates a greater level of micromanagement.
More advanced APM measures will take into account "spamming" or early game finger warm up by ignoring constant reselection of already selected units and buildings, and omitting the first minute or so entirely from their calculation.
