Micromanagement

From The StarCraft 2 Wiki

"Micromanagement" describes the act of selecting and issuing commands to specific units, usually in order to optimize them. Commonly referred to as micro, this is one of the most important aspects of competitive gameplay in StarCraft and WarCraft.

Good micromanagement can be the deciding factor of a match, as any action the player performs by controlling individual units, such as dodging attacks, mining resources, and using special abilities, is a form of micromanagement. One of the more popular examples of this is focus fire, where the player directs multiple units to simultaneously attack a single target. Micro is generally not actions that relate to building, gathering materials or expanding, but rather just the direct control of units that are in, or moving into, combat.

Micro is usually referred to as the opposite of Macromanagement.