A notch is a type of rebate usually found in the edge of boards. It looks more like a v-shape. A notch is formed to hold the legs of the table to the ground. Many other home furniture legs are notched firmly.
Care should be taken to get the exact position of the corners while preparing for a notch. A notch also forms as a connector between two different angled parts, mostly in wooden applications. Strong and useful joints are formed with this notch in hand at the right place.
Apart from the v-shaped notch, there is also a blind notch that serves to hold wooden logs. These wooden logs notched together form a firm bond and grip to the respective applications. A notch can be easily made in a wood with the help of a chainsaw.
Proper measurements would yield a perfect placeholder and serves multiple purposes. A notch is required to complete many applications and make them usable.