Synthetics in fly tying are man-made materials designed to mimic natural elements used in creating artificial flies for fly fishing. These materials, such as synthetic fibers, foam, and rubber, offer versatility and durability, enhancing the realism and effectiveness of flies. Synthetics can imitate various parts of insects, fish, and other prey, including wings, bodies, and tails. They are favored for their consistency, vibrant colors, and resistance to water absorption, making them ideal for crafting flies that perform well in different fishing conditions.