Tennis is a sport usually played between two players (singles) or between two teams of two players each (doubles). 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. Object of the game is to play the ball in such a way that the opponent is not able to play a good return. Tennis is an Olympic sport and is played at all levels of society at all ages. The sport can be played by anyone who can hold a racket, including people in wheelchairs.

The modern game of tennis originated in Birmingham, England in the late 19th century as "lawn tennis" which has close connections to various field/lawn games as well as to the ancient game of real tennis. Up to then, "tennis" referred to the latter sport: for example, in Disraeli's novel Sybil (1845), Lord Eugene De Vere announces that he will "go down to Hampton Court and play tennis. As it is the Derby [classic horse race], nobody will be there". After its creation, lawn tennis spread throughout the upper-class English-speaking population before spreading around the world.

Friendship is a relationship between two people who hold mutual affection for each other. Friendships and acquaintanceship are thought of as spanning across the same continuum. The study of friendship is included in the fields of sociology, social psychology, anthropology, philosophy, and zoology. Various academic theories of friendship have been proposed, including social exchange theory, equity theory, relational dialectics, and attachment styles.

The value of friendship is often the result of friends consistently demonstrating the following:

Friendship was a topic of moral philosophy which was greatly discussed by Plato, Aristotle, and the Stoics. This was less discussed in the modern era, until the re-emergence of contextualist and feminist approaches to ethics. Openness in friendship was seen as an enlargement of the self; Aristotle wrote, "The excellent person is related to his friend in the same way as he is related to himself, since a friend is another self; and therefore, just as his own being is choiceworthy him, the friend's being is choice-worthy for him in the same or a similar way." In Ancient Greek, the same word was used for "friend" and "lover".

Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.

Sound is a sequence of waves of pressure that propagates through compressible media such as air or water. (Sound can propagate through solids as well, but there are additional modes of propagation). During propagation, waves can be reflected, refracted, or attenuated by the medium.

The behavior of sound propagation is generally affected by three things:

When sound is moving through a medium that does not have constant physical properties, it may be refracted (either dispersed or focused).

The perception of sound in any organism is limited to a certain range of frequencies. For humans, hearing is normally limited to frequencies between about 20 Hz and 20,000 Hz (20 kHz), although these limits are not definite. The upper limit generally decreases with age. Other species have a different range of hearing. For example, dogs can perceive vibrations higher than 20 kHz, but are deaf to anything below 40 Hz. As a signal perceived by one of the major senses, sound is used by many species for detecting danger, navigation, predation, and communication. Earth's atmosphere, water, and virtually any physical phenomenon, such as fire, rain, wind, surf, or earthquake, produces (and is characterized by) its unique sounds. Many species, such as frogs, birds, marine and terrestrial mammals, have also developed special organs to produce sound. In some species, these produce song and speech. Furthermore, humans have developed culture and technology (such as music, telephone and radio) that allows them to generate, record, transmit, and broadcast sound. The scientific study of human sound perception is known as psychoacoustics.

Eric Marlon Bishop (born December 13, 1967), professionally known as Jamie Foxx, is an American actor, singer-songwriter, rapper, stand-up comedian, and talk radio host who began playing the piano when he was five years old. As an actor, his work in the film Ray earned him the Academy Award and BAFTA Award for Best Actor as well as the Golden Globe Award for Best Actor in a musical/comedy. He is also a Grammy Award winning musician, producing three albums which have charted highly on the Billboard 200: Unpredictable, which topped the chart, Best Night of My Life and Intuition.

Born in Terrell, Texas, Foxx was raised by his mother's adoptive parents. He performed in high school and was awarded with a scholarship to United States International University. In his twenties, Foxx began performing stand-up at comedy clubs, and eventually joined the cast of In Living Color in 1991; this exposure helped him land film roles and star in his own sitcom, The Jamie Foxx Show. He released his debut album, Peep This, in 1994, but he did not gain significant musical success until 2004 when he was featured in Twista's song "Slow Jamz". Also in 2004, Foxx played critically acclaimed roles in the films Collateral and Ray. He released his second album, Unpredictable, in 2005, which was helped by his collaboration on Kanye West's number-one single "Gold Digger". His third album Intuition was released in 2008 and was anchored by the single "Blame It". Foxx released his fourth studio album, Best Night of My Life, in 2010.

Serena Jameka Williams (born September 26, 1981) is an American professional tennis player and a former world no. 1. The Women's Tennis Association has ranked her world no. 1 in singles on five separate occasions. She became the world no. 1 for the first time on July 8, 2002 and regained this ranking for the fifth time on November 2, 2009. She is the only female player to have won over $35 million in prize money.

Her 27 Grand Slam titles places her ninth on the all-time list: 13 in singles, 12 in women's doubles, and 2 in mixed doubles. She is the most recent player, male or female, to have held all four Grand Slam singles titles simultaneously and only the fifth woman in history to do so. She was also the first woman, along with sister Venus Williams, to hold all four Grand Slam doubles titles simultaneously since Martina Hingis did so in 1998. Her 13 Grand Slam singles titles is sixth on the all-time list. Williams ranks fourth in Grand Slam women's singles titles won during the open era, behind Steffi Graf (22 titles) and Chris Evert and Martina Navratilova (18 titles each). She has won more Major titles in singles, doubles, and mixed doubles than any other active player, male or female.