A float, also called a bobber, is a device used in angling

Angling

Angling is a method of fishing by means of an "angle" . The hook is usually attached to a fishing line and the line is often attached to a fishing rod. Fishing rods are usually fitted with a fishing reel that functions as a mechanism for storing, retrieving and paying out the line. The hook itself...

 that serves two main purposes: it can suspend the bait

Bait (luring substance)

Bait is any substance used to attract prey, e.g. in a mousetrap.-In Australia:Baiting in Australia refers to specific campaigns to control foxes, wild dogs and dingos by poisoning in areas where they are a problem...

 at a predetermined depth, and it can serve as a bite indicator. They are often used in conjunction with a fishing sinker. Fishing with a float is called float fishing.

Floats come in different sizes and shapes. They are usually brightly coloured so they are easy to see.

• The waggler is a thin tube of plastic with a line threaded through an eye at the bottom. It is commonly used as a running line float on still waters.
• The avon has a somewhat large and oval-shaped hollow area near the tip. Extra shot is added to the line so only the tip shows, allowing the line to be cast further. Avons are used in slow-flowing water.
• Long, thin floats are very sensitive and are used for coarse fishing
  Coarse fishing
  Coarse fishing is a term used in the United Kingdom and Ireland for angling for coarse fish, which are those types of freshwater fish other than game fish . The sport and the techniques used are particularly popular in the United Kingdom and mainland Europe.-History:The term "coarse fishing"...
  
  

Directional floats

There are also floats that allow directional control on rivers. If the current in the river is not too fast, it is possible with these floats to steer left or right down stream. In this way, areas can be reached which could not be reached in any other way. This eliminates the need for multiple casts. Directional floats can also be made to work in still water, such as lakes. If there is no current, the float is reeled in at about one quarter of the normal speed, using a travel of 4 inches for each 1 inch of reel. This reduces the number of times needed to cast by a factor of four. They can be used to steer under docks or trees.