Attaching a float to the line to indicate a bite on the hook has long been a way to know when a fish is nibbling your bait. Floats not only show you when something is biting, they also can be used to suspend the hook at a certain depth where you think the fish are feeding, and to keep the bait out of trash on the bottom. When you're fishing water with a current, a float can carry your bait down the stream, offering it to many fish.
Kinds of Floats
For many years floats were made mostly of cork and many people still call them corks, no matter what they're made of. There are different shapes of floats for different kinds of fishing, too. Traditional cork floats are usually shaped like a bottle cork and have a split in the side to run your line through. Plastic floats come in all shapes and sizes, but round red-and-white ones have been the most common for a long time. They have a wire hook running through them with a spring to let them hold your line tight.
Styrofoam floats are very common now and they can be found in any shape you want. Round or egg-shaped floats are very common and they either have a spring-loaded clip or a hole through the middle for your line. Corks with a hole through them work well as slip floats or you can stick a small rod in them to hold your line in place. They're usually very colorful so they can be seen easily on the water.
Another name for floats is bobbers because that's the motion they have sitting on the surface of the water. It's very relaxing watching a bobber gently moving up and down with the ripples on the water, but it gets real exciting when the bobbing lets you know a fish is interested in your bait. Most kids find watching a bobber a good way to fish, so it is a good way to get them started.
Quill floats are long and thin and your fishing line attaches to one end. They will quiver and stand up with the slightest bite so they're used for match fishing and at other times when you need to detect the slightest nibble on your bait. The original ones were made from porcupine quills.
Other Uses for Floats
A float also adds weight to help in casting light bait. Some are even called casting bubbles and have a clip on each end to attach your main line and leader. A fly or very light bait can be added to the end of the leader and cast with spinning or even bait-casting equipment.
Some floats have concave faces at one end with a place to attach your main line and a tapered end at the other to attach the leader. When you pull the main line the float pops and gurgles in the water, attracting fish. The noise resembles fish chasing baitfish on the surface. These floats often have a lead weight in them to make them stand up and also to help in casting them long distances.
As with sinkers, use the smallest float that gets the job done. Don't try to suspend a cricket under a float the size of a softball because it will make too much noise hitting the water and its size may spook the fish. You'll need one that size to float a spreader rig across flats in bays when fishing for flounder, though. Match the size of your float to the job you want it to do.