Synchronized swimming (in British English, synchronised swimming), also known as artistic swimming, is a sport where swimmers perform a synchronized choreographed routine, accompanied by music. The sport is governed internationally by World Aquatics (formerly known as FINA). It has traditionally been a women's sport, although FINA introduced a new mixed-gender duet competition that included one male swimmer in each duet at the 2015 World Aquatics Championships and European Aquatics introduced men's individual events at the 2022 European Aquatics Championships. From 2024, men are able to compete in the team event at the Olympics.

Synchronized swimming has been part of the Summer Olympics program since 1984, featuring both women's duet and team events. In 2017, under the instruction of the International Olympic Committee (IOC), FINA renamed the sport from "synchronized swimming" to "artistic swimming" – a decision that has faced controversy. The new official name has yet to gain general acceptance beyond the core of the sport.

In 2022, the synchronized-swimming rules were overhauled to reduce subjectivity in judging. This change brings the sport's rules closer to the sport of artistic gymnastics and also figure skating.

Routines are composed of elements and transitions. Under World Aquatics rules, they are from two to three minutes long, with competition category determining routine length. There is a penalty for touching the bottom of the pool during the routine. Swimmers are synchronized to each other and to the music. Routines are judged on execution and artistic impression and a pre-determined degree of difficulty. The degree of difficulty is declared prior to performing, and may decrease in the final score if athletes fail to complete the declared movements. Each routine has a coach card, where the elements and their difficulty are declared in order of performance.

There are three types of elements: hybrid, acrobatic, and technical required element. Each category of routine has a certain number of elements which must be performed. Elements have a difficulty score which is declared prior to the routine's performance. If the element is not performed as it is declared, the element will receive a base mark, reducing its difficulty to its base value. A panel of judges scores each element for execution, which is multiplied by the difficulty of the element, making it a significant loss to the routine's score if an element receives a base mark.

A hybrid is a combination of leg movements, with the head and torso underneath the water. It is defined as five or more movements performed with the head underneath the hips. A hybrid consists of skills, with each skill having a difficulty value determined by World Aquatics. The difficulty of the skills is added to the base value (0.5) to get the declared difficulty. An example of how a hybrid could receive a base mark would be if a skill with a 360 degree spin is declared, but the swimmer doesn't spin the full amount.

An acrobatic is a movement where one or more swimmers are lifted out the water by their teammates. They are also referred to as lifts or highlights.

A technical required element is a predetermined movement that must be performed in a technical routine. They are visually similar to hybrids, but will stay the same across routines in the same category. The required elements vary in different categories, so teams and duets and solos all have different required elements.