Equipment can help improve technique by focusing on specific aspects of your stroke. Many drills have accompanying equipment for different levels of the drill. Equipment is also recommended when you are kicking and pulling to get the greatest benefit from each swim. Many pools will have a bin full of pull buoys and kickboards for swimmers to use, and some will also have paddles and fins.
A floatation device that goes between your legs to help your legs float at the surface of the water. In general, pull buoys are held between the thighs. They can also be held between the ankles, which is common when focusing on body position.
A floatation device that is used to work on your kicking in swimming. Kickboards are held extended out in front of a swimmer with both hands, effectively forcing the swimmer to propel themselves only with their kick.
Hand paddles increase the effective size of your hands to add more power and resistance to your stroke. Paddles vary in size, and it is best to choose paddles that are not too big for your hands to minimize the risk of a shoulder injury.
Flippers that go on your feet to add propulsion. Using fins is a great way to improve kick cadence and power.