The top area of the field is the chief and the bottom the base. The shield is viewed as if being borne, so the viewer's left is the right, or dexter, and the viewer's right, the sinister. The top centre is the honour point, the middle centre the fess point, and the base centre the nombril point. To describe an achievement is to blazon it. The terms of blazon are in general a mixture of English and old French.
Blazon is based in conventions that make it terse and unequivocal.
Charges always face dexter, for example, and three charges on a shield are placed two in chief and one in base unless otherwise blazoned. There are many such conventions. From the foregoing. On a trunk of a tree, lying fessways, a branch issuant from the dexter end, proper, a falcon, wings expanded, argent, beaked, belled and legged, or. Usage varied from next to none early on, to primarily in French during the Tudor Era, to mainly in Latin by the 16th Century.