Most hooks in your fly fishing tackle are made of some kind of steel, from iron to stainless. Saltwater hooks are generally of rust-resistant material, while freshwater hooks don't need that because they don't rust as fast. Some alloys help the hook stay sharp while others make it very tough enough to put up a good fight with a large fish.
Stainless steel hooks don't rust either in your tackle box or in a fish's mouth. You should note, though that if you simply cut the line when a fish is hooked deep in the throat, the stainless steal hooks left behind may not deteriorate fast enough for the fish to live.
A Snelled hook is the generic name for a hook with a leader tied to it in a special way. The line is tied to the shaft instead of the eye. Some Snelled hooks don't even have an eye but rather spade-type foot at the end of the shank. The line is wrapped around the shaft and tied in order to pull in a straight line. A Snelled has some advantages over standard hooks. The knot which attaches the hook to the line is very strong and makes contact with the hook in more than one place, meaning there is a slimmer chance that the line will break. The way it's attached puts a more direct pull on the hook, making for a better hook set and more control during the fight. The opposite end of the leader is usually tied in a loop so you can swiftly attach it to your line with a loop knot or snap.
We do regular postings on the subject of fly fishing tackle, so please check our archives, and look out for more in the future.