A feeder is a perforated container, into which bait is placed so that it can leak out at a controlled rate, thereby attracting more fish to the area. Feeder fishing is one on the many styles of fishing which fall under the umbrella of legering. To begin with, Ill list several types of feeder readily available.
Maggot Feeder
There are lots of maggot feeder size variations. They are available with a closed top and bottom, and are peppered with holes to allow maggots and casters to escape freely.
The Cage
The cage is a variation of the open ended feeder, constructed from open cell wire/ metal, also used for ground bait and or sandwich feeding.
Sandwiching
Sandwiching describes partially filling your feeder with ground bait, placing in a few bait samples - maggots, casters, small pellets etc -and topping it of with your ground bait, providing an explosion of bait in your swim. This method has proved deadly for many species, particularly barbel and chub on rivers.
Vary the size of your feeder and its contents according to your environment. You might use a tiny open or maggot feeder in winter for carp or silver fish in clear pools, when fish are spooky or only feeding sporadically, so as to stimulate but not overfeed them.
The Paternoster
There are also many ways to attach your feeder to your end tackle, many notable anglers use the paternoster rig. To use a paternoster, tie your feeder to the end of your mainline or with a snap swivel (which allowing you to change the size of your feeder quickly, if needs be). Tie a hook length to you main line using a four-turn water knot or similar. The length of tail will largely depend on your target species. Generally I use longer hooklinks for bream and silver fish, up to 24inchs (60cm) and reduce it for the larger the species. On static waters many anglers will give a couple of turns of the reel after the tackle has reached the bottom, to drag the hooklink over the deposited bait.
Safety Rig
Most anglers will use some kind of safety rig when fishing for carp. These safe rigs are available from all good tackle shops. I also use them for my feeder fishing. I attach a large eyed swivel to my chosen feeder, which is then in turn attached to the safe rig lead retainer lug.
As with all types of fishing try to keep your equipment balanced, rod to line to hook to bait etc.
Try to remember and lightly touch the line on the reel - its called feathering - just before your end rig enters the water. This will allow your hooklink to move ahead of your feeder giving you good presentation and help to prevent tangles.
The most important factor is not your equipment, or how you use it. Its confidence. So, If you find a style that regularly catches you fish, stick with it. Of Coarse try different methods, but you will always have your favourite to fall back on.