The Master Point is the part of the anchor that holds all the load (practically where every climber needs to be connected to the safety system, directly or indirectly). This can be in a variety of situations, such as, Top rope, direct tie-in with PAS or re-directional pieces of gear.
A master point needs to be tied with an overhand knot or figure eight knot. Tying the knot guarantees that the anchor stays non-extendable in the case of 1 piece failing. Before tying the master point knot, the anchor rope/sling has to be set into the correct “direction of pull” – this is the direction from where the forces are applied to the master point.
Other anchoring methods such as “sliding X” or “Equalette” also offer a master point but they are extendable in case of one piece of gear failing – extension is never desired as they shock-load the remaining part/s of the anchor. Benefits and disadvantages are described in our sliding X and Equalette articles on the Chillino Rock Climbing pro tips page.