An artificial fly or fly lure is a type of fishing lure. It is usually used in the sport of fly fishing. Artificial flies imitate insects or other things fish eat. Artificial flies are made by fly tying. This is an art in which furs, feathers, thread or any of very many other materials are tied onto a fish hook.
There are thousands of different fly patterns (kinds) available. Many imitate a particular insect a fish might recognize. Other patterns don't look like any insect, but attract fish anyway.