Tennis shots
In tennis, there are a variety of types of shots (ways of hitting the ball) which can be categorized in various ways. The grip you place on will help you have different types of shots, the lower your grip means that the ball is most likely going to be a ground stroke. According to William T. Tilden, "All tennis strokes, should be made with the body' at right angles to the net, with the shoulders lined up parallel to the line of flight of the ball." The serve is the opening shot of a point. Groundstrokes are hit  after the ball has already bounced, and can be either forehands or backhands depending on which direction the racket is swung relative to the body. A lob is a groundstroke hit well over the head of an opponent who is positioned at the net. A passing shot is a groundstroke that is hit out of reach of an opponent at the net far to his left or right. A "cross-court shot" is a shot hit from the left (or right) side of one player's court to the left (or right) side of the other player's court (from  each player's own point of view), so that it crosses the lengthwise centerline of the court. A "down-the-line shot" is one that is hit more or less parallel to, and near to, one of the sidelines, so that it never crosses the centerline. Shots hit during a point without the ball having bounced are called volleys, while shots hit just a split second after the ball bounces are called half volleys. A smash is hit with the racket well above one's head with great velocity. A drop shot is a groundstroke or volley that is hit  lightly so that it barely goes over the net. A "slice" is a groundstroke or volley hit with backspin, while a "topspin shot" is a groundstroke or occasionally a volley hit with topspin. Thus tennis shots can be categorized according to when they are hit (serve, groundstroke, volley, half volley), how they are hit (smash, forehand, backhand, flat, side spin, block, slice, topspin shot), or where they are hit (lob, passing shot, dropshot, cross-court shot, down-the-line shot). All shots that pass either over or around the net and land anywhere within the confines of the court, lines  included (except for serves, which need to land inside the designated service box), are considered "good". Shots that touch the net and then land in their designated area are also considered "good", with the exception of serves. Serves that fall into the service box after touching the net are called "service lets", and the server simply serves again, without any impact on the scoring. Serve. A serve (or, more formally, a service) in tennis is a shot to begin the point. The most common serve is used is an "overhead serve". It is initiated by tossing the ball into the  air over the server's head and hitting it when the arm is fully stretched out (usually near the apex of its trajectory) into the diagonally opposite service box without touching the net. The server may employ different types of serve: a flat, a top-spin, an American twist (or kick), or a slice serve. A severely sliced serve is sometimes called a sidespin. Some servers are content to use the serve simply to initiate the point; advanced players often try to hit a winning shot with their serve. A winning serve that is not touched by the opponent is  called an "ace". Forehand. The "forehand" is struck from the dominant side of the body by swinging the racquet in the direction of where the player wants to place the shot. It is called a forehand because the racquet is held in such a way that if one were to strike the ball without the racquet, it would hit the palm of your hand. This is the opposite side from a "backhand". It is considered the easiest shot to master, perhaps because it is the most natural stroke. Beginners and advanced players often have better forehands than any other shots  and use it as a weapon. There are various grips for executing the forehand and their popularity has fluctuated over the years. The most important ones are the "Continental", the "Eastern", and the "Western". The key differences between grips are the different angles they create between the angle of your palm and the angle of your racquet face. You are used to sensing the direction your palm is facing, so your palm makes the most intuitive basis for sensing the direction your racquet is facing. For a number of years the small, apparently frail 1920s player Bill Johnston was considered  by many to have had the best forehand of all time, a stroke that he hit shoulder-high using a "western" grip. Few top players used the "western" grip after the 1920s, but in the latter part of the 20th century, as shot-making techniques and equipment changed radically, the "western" forehand made a strong comeback and is now used by many modern players. No matter which grip is used, most forehands are generally executed with one hand holding the racquet, but there have been fine players with two-handed forehands. In the 1940s and 50s the Ecuadorian/American player  Pancho Segura used a two-handed forehand to devastating effect against larger, more powerful players, and many female and young players use the two-handed stroke today. Backhand. The "backhand" is struck from the non-dominant side of the body by bringing the racquet across the body (showing the "back" of your hand to the opponent) and swinging the racquet away from one's body in the direction of where the player wants the ball to go. It is generally considered more difficult to master than the forehand. It can be executed with either one or both hands. For most  of the 20th Century it was performed with one hand, using either an "eastern" or a "continental" grip. The first notable players to use two hands were the 1930s Australians Vivian McGrath and John Bromwich. The Two handed backhand was used more often since it allowed easy access to power and control. Players such as Venus Williams, Serena Williams, Maria Sharapova, and Andre Agassi have used this stroke to its highest potential to win many grandslams. Two hands give the player more power so it provides the player with an advantage on power-focused shots. However, one hand is useful  in that it can generate a slice shot, applying backspin on the ball to produce a low trajectory bounce. The player long considered to have had the best backhand of all time, Don Budge, had a very powerful one-handed stroke in the 1930s and '40s that imparted topspin onto the ball. Ken Rosewall, another player noted for his one-handed backhand, used a deadly accurate slice backhand with underspin through the 1950s and '60s. A small number of players, notably Monica Seles, use two hands on both the backhand and forehand sides. Volley. A volley is made in the  air "before" the ball bounces, generally near the net or inside of the service line. Volleys consist of the forehand volley and backhand volley and are usually made with a stiff-wristed "punching" motion to hit the ball into an open area of the opponent's court. The half volley is made by hitting the ball on the rise just after it has bounced, once again generally in the vicinity of the net. From a poor defensive position on the baseline, the lob can be used as either an offensive or defensive weapon, hitting the ball high and deep into  the opponent's court to either enable the lobber (the player hitting the lob) to get into better defensive position or to win the point outright by hitting it over the opponent's head. If the lob is not hit deeply enough into the other court, however, the opponent may then hit an overhead smash, a hard, serve-like shot (hit over the players head), to end the point. Finally, if an opponent is deep in his court, a player may suddenly employ an unexpected drop shot, softly tapping the ball just over the net so that the opponent is  unable to run in fast enough to retrieve it. Other shots. The "tweener" is a rarely used shot in which a player hits the ball between his/her legs, generally with their back facing the net. Also known as the between-the-legs shot or the "Gran Willy" (after Guillermo Vilas, an early pioneer), it is generally performed when the player must run to recover a lob and has no time to turn back to face the net before attempting their return. The shot was pioneered in the 1970s by Guillermo Vilas and Yannick Noah, both of whom claimed to  have invented it; later players to use it include Ilie Năstase, Boris Becker, Gabriela Sabatini (whose version was called the "Sabatwini"), Andre Agassi, Roger Federer, Rafael Nadal, Novak Djokovic and Nicholas Kyrgios who helped popularize the shot. Forward-facing between-the-legs shots are also occasionally employed; they are sometimes called "front tweeners". The "Bucharest Backfire" is an over-the-shoulder backward shot, generally used to recover lobs. Tennis writer Bud Collins named it in honor of Romanian player Ilie Năstase, who popularized it. Another seldom used shot is a behind-the-back shot, which, as its name suggests, is  hit by crossing the preferred arm across his/her back without swinging. It is generally hit while stationary, and can occasionally be used as a volley shot. It is challenging to master as it is hard to predict where the ball may strike the racket, if not at all in most cases. Accurately hitting the ball to the desired location is also extremely hard to do. The "Bowl Smash", also known as the "Skyhook Smash", or the "Skyhook", is a variation of the "Bucharest Backfire", showcased by Jimmy Connors. It consists on hitting a "Bucharest Backfire" while jumping, in order  to recover lobs earlier, given the additional vertical reach provided by the jump. The player performing that shot may end up doing a full 360° spin in the process. Roger Federer and more frequently Rafael Nadal are known for performing this shot, even during official matches for the latter.