A swimmer is someone who propels themselves through water using their arms, legs, and body. Swimmers might glide through a pool doing laps for exercise, race against others in competitions, or simply splash around at the beach on a summer day.

Some swimmers train seriously, learning specific strokes like freestyle, backstroke, breaststroke, or butterfly. Competitive swimmers practice for hours, building strength and perfecting their technique to shave fractions of a second off their times. Olympic swimmers like Michael Phelps and Katie Ledecky have become some of the most decorated athletes in history through years of dedicated training.

Other swimmers enjoy the water more casually: swimming to cool off, playing games with friends, or exploring underwater with goggles and a snorkel. Many people swim for fitness because it exercises the whole body without putting stress on joints.

The word can also describe animals that move through water, like fish, dolphins, and sea turtles. Some animals are strong swimmers by nature, while others (like dogs) can swim but prefer solid ground. Humans aren't natural swimmers like dolphins, but we can learn to swim very well with practice and proper instruction.