- Not available on that edition (the reason is in the tooltip)
- Depends on the setting, your class or another addon (details in the tooltip)
What it does
Checks if your character is currently moving, based on your movement speed.
Why you might use it
Check whether your character is moving. In fights with a lot of movement it lets a rotation switch to instant spells on the move, such as Fire Blast or Ice Lance for a Mage, Arcane Shot for a Hunter or Shadow Word: Pain for a Priest, and keep cast-time spells like Fireball or Aimed Shot for when you stand still. It tests only your own movement, not your target's. On Retail and Forever, if the game hides your movement speed, the condition is unavailable.
Example
you are moving
Settings
What each setting in the condition editor means, from the game's own help.
Matches while your character is moving, based on current movement speed. It does not test the movement of your target.