Mountaineering Basics: Communication
Succinct voice commands allow climbers to communicate even when they can not see each other.

Mountaineering Basics: Knots
Climbers rely most heavily on a dozen or so different knots and some hitches: Figure-8, Clove Hitch, Overhand Knot, Water Knot, Square Knot.

Mountaineering Basics: Position/Stance: Facing in/out
When belaying a follower, it's normal to face out, usually with the anchor at your back. When belaying a leader, the choices are more complex.

Mountaineering Basics: Position/Stance: Position & Anchor
Make sure you are tied in as close as feasible to the anchors, with no slack, so that you won't be jerked about by a severe fall.

Mountaineering Basics: Position/Stance: the Stance
In most cases it is primarily the stance that prevents you from being jerked around by a fall or reduces the consequences of being tossed about.

Mountaineering Basics: Rope Handling
Rope handling takes practice. When belaying the leader, never let the rope get taut, because that would impede the climber's next move.