Elytra is a pair of wings worn in the chest slot, and the item that ends walking as the main way to cross a world. There is no recipe for it, so every search for how to craft elytra ends in the same place: an item frame aboard an end ship, the small vessel that generates beside some end cities out on the outer End islands.
Gliding starts with a jump from height and a second press of the jump key on the way down. After that you trade height for distance — aim down to build speed, level out to stretch the glide. Firework rockets used in hand push you forward and hold your altitude, which is what makes Elytra genuine transport rather than a long descent, and a trident with Riptide can relaunch you in rain or open water when the rockets run out.
Elytra wears down as you fly but never breaks. When its durability runs out it simply stops working until repaired, so a worn pair is never lost. Repair it with phantom membranes in an anvil, or take the elytra enchantments that matter — Mending, which restores it from the experience you collect, and Unbreaking, which lengthens the gap between repairs. It accepts nothing else beyond the two curses.
Because it takes the chest slot, flying means going without a chestplate, so most players carry armour and swap it in before a fight. Two things end early flights: rockets running out far from home, and landing at speed, since striking a wall while gliding deals damage in proportion to how fast you were moving.