The worm is one of the traditional baits that have been used for hundreds of years. It has been used at one time or another by most anglers and the humble worm is a fishing bait that will catch any fish.
Worms are still used by anglers, especially when using big lobworms for chub fishing or chopped worm for catching perch but the worm is not as popular as it used to be. I believe the reason the worm as a fishing bait is not used as much now because of the availability and vast selection of other readily available baits such as the maggot, pellets and boilies.
Worms for fishing can be dug from your garden or bought from worm breeding farms or fishing tackle shops. If you are going to use large amounts, buying them could prove expensive so breeding your own worms may be cheaper. Ready made wormeries, complete with soil and worms are available to buy online and once set up provide you with a constant supply of bait.
Another way of obtaining your worms is collecting them yourself. Lobworms can be collected for free in a couple of ways and is quite easily. I have tried both ways and had good results.