Net sport may refer to any of several sports where a net

Net (device)

A net, in its primary meaning, comprises fibers woven in a grid-like structure, and is very infrequently mentioned in discussions of philosophy. It blocks the passage of large items, while letting small items and fluids pass...

 is a standard part of the game. The term usually applies to sports where the net separates the opponents.

Net sports usually include:

• racquet sports such as tennis
  Tennis
  Tennis is a sport usually played between two players or between two teams of two players each . Each player uses a racket that is strung to strike a hollow rubber ball covered with felt over a net into the opponent's court. Tennis is an Olympic sport and is played at all levels of society at all...
  
  , badminton
  Badminton
  Badminton is a racquet sport played by either two opposing players or two opposing pairs , who take positions on opposite halves of a rectangular court that is divided by a net. Players score points by striking a shuttlecock with their racquet so that it passes over the net and lands in their...
  
  , pickleball
  Pickleball
  Pickleball is a racquet sport which combines elements of badminton, tennis, and table tennis. The sport is played on a court with the same dimensions as a doubles badminton court. The net is similar to a tennis net, but is mounted two inches lower...
  
   and table tennis
  Table tennis
  Table tennis, also known as ping-pong, is a sport in which two or four players hit a lightweight, hollow ball back and forth using table tennis rackets. The game takes place on a hard table divided by a net...
  
  , but not squash
  Squash (sport)
  Squash is a high-speed racquet sport played by two players in a four-walled court with a small, hollow rubber ball...
  
   or racquetball
  Racquetball
  For other sports often called "paddleball", see Paddleball .Racquetball is a racquet sport played with a hollow rubber ball in an indoor or outdoor court...
  
  
• volleyball
  Volleyball
  Volleyball is a team sport in which two teams of six players are separated by a net. Each team tries to score points by grounding a ball on the other team's court under organized rules.The complete rules are extensive...
  
  

In each of these sports, the ball or bird must go over the net to be in play.

Although basketball

Basketball

Basketball is a team sport in which two teams of five players try to score points by throwing or "shooting" a ball through the top of a basketball hoop while following a set of rules...

, hockey

Hockey

Hockey is a family of sports in which two teams play against each other by trying to maneuver a ball or a puck into the opponent's goal using a hockey stick.-Etymology:...

, water polo

Water polo

Water polo is a team water sport. The playing team consists of six field players and one goalkeeper. The winner of the game is the team that scores more goals. Game play involves swimming, treading water , players passing the ball while being defended by opponents, and scoring by throwing into a...

 and other sports have netting around the goal area designed to more clearly indicate when goals are scored, they are not usually considered "net sports". Similarly, lacrosse stick

Lacrosse stick

A lacrosse stick or crosse is a long-handled racket used to play the sport of lacrosse. Players use the lacrosse stick to handle the ball and to strike at opposing players...

s have a loose netting that is used to catch and fling the ball, but again lacrosse

Lacrosse

Lacrosse is a team sport of Native American origin played using a small rubber ball and a long-handled stick called a crosse or lacrosse stick, mainly played in the United States and Canada. It is a contact sport which requires padding. The head of the lacrosse stick is strung with loose mesh...

 is not usually considered a "net sport".

The Los Angeles Daily Times reports: "Net sports are unique in that the equipment is light, portable and affordable, and partners and opponents are easy to find. The sports are easy to learn, and the social aspect of the game[s] appeals to those who find the health club to be an isolationist palace of mirrors."

The three "favorite" net sports (tennis, badminton, and volleyball) usually involve arching of the back

Human back

The human back is the large posterior area of the human body, rising from the top of the buttocks to the back of the neck and the shoulders. It is the surface opposite to the chest, its height being defined by the vertebral column and its breadth being supported by the ribcage and shoulders...

 when serving

Serve (tennis)

A serve in tennis is a shot to start a point. A player begins a serve by tossing the ball into the air and hitting it into the diagonally opposite backside box without being stopped by the net. The ball can only touch the net on a return and will be considered good if it falls on the opposite side...

 or spiking/smashing

Smash (tennis)

A smash in tennis is a shot that is hit above the head with a serve-like motion. A smash can usually be hit with great force relatively safely and is often a shot that ends the point. Most smashes are hit fairly near the net or in mid-court before the ball bounces, generally against lobs that have...

the ball or bird.