Mounted Combat
For example, if you're mounted on an animal and you make three attacks, your mount would remain stationary since you didn't command it. If you instead spent your first action to Command an Animal and succeeded, you could get your mount to Stride. You could spend your next action to attack or to command the mount to attack, but not both.
Mounted Attacks
You occupy every square of your mount's space for the purpose of making attacks. If you were a Medium creature on a Large mount, you could attack a creature on one side of your mount, then attack on the opposite side. On a Medium or smaller mount, use the normal reach of an attack. On a Large or Huge mount, you can attack any square adjacent to the mount if you have 5- or 10-foot reach, or any square within 10 feet of the mount (including diagonally) if you have 15-foot reach. Use the adjusted reach for determining flanking and other rules that depend on reach.
Mounted Defenses
Because you can't move your body as freely while you're riding a mount, you take a –2 circumstance penalty to Reflex saves while mounted. Additionally, the only move action you can use is the Mount action to dismount.