What is grafting? Grafting is the merging of two parts of the plant the rootstock and the scion. The rootstock is the bottom part of the plant that consists of a root and the trunk. The scion is the upper part of the plant consist of an upper trunk and branches. In grafting, we can select the best quality of both rootstock and scion that is suitable for climate and soil conditions in a certain environment. If you have a tree that doesn't bear a great fruit but have a strong root system you can cut it and graft a scion from a better variety of the same genome so that you can harvest better sweet fruits in a short period because of the established root system of the rootstock.
