Training raptors (birds of prey) is a complex undertaking. Books containing advice by experienced falconers are still rudimentary at best. Many important details vary between individual raptors, species of raptors and between places and times. The keeping and training of any raptor is strictly and tightly regulated by U.S. state and federal laws. Anyone in the USA who is interested in flying raptors must seek out a state and federally licensed falconer to sponsor them through an apprenticeship period lasting two years at a minimum, and often considerably longer.

The bird wears:

Falcons (the long-wing family of raptors) are tethered perched on a block; large owls (during training only) and short-winged and broad-winged hawks are tethered to a bow perch or round perch, when not allowed to fly free in their mews, an Old English word for a raptor's chamber. (The term is "mews" whether singular or plural; the word "mews" came from French muer which means "to change" or "to molt", i.e. where the hawk was kept while it was molting.)

There are three styles of jesses. Traditional is a single strap specially knotted onto the bird. Aylmeri is a two part restraint featuring an anklet that is grommeted on and a removable jess strap. Some Aylmeri jess straps have dental rubber bands on them to make it more difficult for the bird to pull out the jess, but they are still removable if the bird gets caught up outdoors. The third type of jesses is a combination of the two, referred to as "false Aylmeri." These use an anklet as well, but a brass eyelet is slipped through far enough away that the toes will not get caught in it; there are two straps attached to the anklet, flying jesses and mews jesses. Both can be removed. A good reference on these jesses is "Care And Management of Captive Raptors" by Lori Arent & Mark Martell, published by the University of Minnesota: this guide is very popular with zoos and wildlife centers, though it is not a traditional falconry book.

The singular of "jesses" is correctly "jess", but one jess is often mistakenly called a "jessie", by wrong back-formation from "jesses" treated as "jessies", which would be pronounced the same.

Nylon Aylmeri jesses have recently grown in popularity. Thinner, lighter, and stronger, they do not rot or need oiling to stay supple. The anklets are grommetted on, like their leather counterparts, but instead of a folded button keeping the straps from falling through the anklets, a knot is used. The end of the knot is melted with a cigarette lighter to keep it from fraying. In order to form the loops the swivel or clips will attach to, a nylon parachute cord is hollowed out, threaded up through itself using an awl, and knotted.

The swivel is to prevent tangling and twisting of the leash or tether when the bird is active but not hunting. The swivel consists of two parts that twist freely, each with a metal hoop on the end. The swivel may be traditional, or modified. The modified swivel has much larger metal hoops than the traditional. While swivels have been made of cloth or other materials in the past, most modern falconers use metal swivels.

When using Aylmeri jesses, there are usually two sets of straps; the mews strap, for manning and tethering the bird, and flying straps. The flying straps are lighter and smaller for hunting; the mews straps are heavy and less likely to break with stress.