MD Sports Official Size 15mm 4 Piece Indoor Table Tennis, Accessories Included, Blue/White

4 (four) is a number, numeral and digit. It is the natural number following 3 and preceding 5.

4 is the smallest square number > 1, the smallest semiprime and composite number, and the 3rd highly composite number.

The number 4 is considered unlucky in many East Asian cultures.

Blue is one of the three primary colours in the RYB colour model (traditional colour theory), as well as in the RGB (additive) colour model. It lies between violet and cyan on the spectrum of visible light. The term blue generally describes colours perceived by humans observing light with a dominant wavelength that's between approximately 450 and 495 nanometres. Most blues contain a slight mixture of other colours; azure contains some green, while ultramarine contains some violet. The clear daytime sky and the deep sea appear blue because of an optical effect known as Rayleigh scattering. An optical effect called the Tyndall effect explains blue eyes. Distant objects appear more blue because of another optical effect called aerial perspective.

Blue has been an important colour in art and decoration since ancient times. The semi-precious stone lapis lazuli was used in ancient Egypt for jewellery and ornament and later, in the Renaissance, to make the pigment ultramarine, the most expensive of all pigments. In the eighth century Chinese artists used cobalt blue to colour fine blue and white porcelain. In the Middle Ages, European artists used it in the windows of cathedrals. Europeans wore clothing coloured with the vegetable dye woad until it was replaced by the finer indigo from America. In the 19th century, synthetic blue dyes and pigments gradually replaced organic dyes and mineral pigments. Dark blue became a common colour for military uniforms and later, in the late 20th century, for business suits. Because blue has commonly been associated with harmony, it was chosen as the colour of the flags of the United Nations and the European Union.

In the United States and Europe, blue is the colour that both men and women are most likely to choose as their favourite, with at least one recent survey showing the same across several other countries, including China, Malaysia, and Indonesia. Past surveys in the US and Europe have found that blue is the colour most commonly associated with harmony, confidence, masculinity, knowledge, intelligence, calmness, distance, infinity, the imagination, cold, and sadness.

Indoor(s) may refer to:

• the interior of a building
• Indoor environment, in building science, traditionally includes the study of indoor thermal environment, indoor acoustic environment, indoor light environment, and indoor air quality
• Built environment, the human-made environment that provides the setting for human activity
• Indoor athletics
• indoor games and sports

An official is someone who holds an office (function or mandate, regardless of whether it carries an actual working space with it) in an organization or government and participates in the exercise of authority (either their own or that of their superior or employer, public or legally private). An elected official is a person who is an official by virtue of an election. Officials may also be appointed ex officio (by virtue of another office, often in a specified capacity, such as presiding, advisory, secretary). Some official positions may be inherited. A person who currently holds an office is referred to as an incumbent. Something "official" refers to something endowed with governmental or other authoritative recognition or mandate, as in official language, official gazette, or official scorer.

Piece or Pieces (not to be confused with peace) may refer to:

Size in general is the magnitude or dimensions of a thing. More specifically, geometrical size (or spatial size) can refer to three geometrical measures: length, area, or volume. Length can be generalized to other linear dimensions (width, height, diameter, perimeter). Size can also be measured in terms of mass, especially when assuming a density range.

In mathematical terms, "size is a concept abstracted from the process of measuring by comparing a longer to a shorter". Size is determined by the process of comparing or measuring objects, which results in the determination of the magnitude of a quantity, such as length or mass, relative to a unit of measurement. Such a magnitude is usually expressed as a numerical value of units on a previously established spatial scale, such as meters or inches.

The sizes with which humans tend to be most familiar are body dimensions (measures of anthropometry), which include measures such as human height and human body weight. These measures can, in the aggregate, allow the generation of commercially useful distributions of products that accommodate expected body sizes, as with the creation of clothing sizes and shoe sizes, and with the standardization of door frame dimensions, ceiling heights, and bed sizes. The human experience of size can lead to a psychological tendency towards size bias, wherein the relative importance or perceived complexity of organisms and other objects is judged based on their size relative to humans, and particularly whether this size makes them easy to observe without aid.

Table may refer to:

• Table (database), how the table data arrangement is used within the databases
• Table (furniture), a piece of furniture with a flat surface and one or more legs
• Table (information), a data arrangement with rows and columns
• Table (landform), a flat area of land
• Table (parliamentary procedure)
• Table (sports), a ranking of the teams in a sports league
• Tables (board game)
• Mathematical table
• Table, surface of the sound board (music) of a string instrument
• Al-Ma'ida, the fifth surah of the Qur'an, occasionally translated as “The Table”
• Calligra Tables, a spreadsheet application
• Water table

Tennis is a racket sport that is played either individually against a single opponent (singles) or between two teams of two players each (doubles). Each player uses a tennis racket strung with a cord to strike a hollow rubber ball covered with felt over or around a net and into the opponent's court. The object is to manoeuvre the ball in such a way that the opponent is not able to play a valid return. If a player is unable to return the ball successfully, the opponent scores a point.

Playable at all levels of society and at all ages, tennis can be played by anyone who can hold a racket, including wheelchair users. The original forms of tennis developed in France during the late Middle Ages. The modern form of tennis originated in Birmingham, England, in the late 19th century as lawn tennis. It had close connections to various field (lawn) games such as croquet and bowls as well as to the older racket sport today called real tennis.

The rules of modern tennis have changed little since the 1890s. Two exceptions are that until 1961 the server had to keep one foot on the ground at all times, and the adoption of the tiebreak in the 1970s. A recent addition to professional tennis has been the adoption of electronic review technology coupled with a point-challenge system, which allows a player to contest the line call of a point, a system known as Hawk-Eye.

Tennis is played by millions of recreational players and is a popular worldwide spectator sport. The four Grand Slam tournaments (also referred to as the majors) are especially popular and are considered the highest level of competition for the sport. These tournaments are the Australian Open, played on hardcourts; the French Open, played on red clay courts; Wimbledon, played on grass courts; and the US Open, also played on hardcourts. Additionally, tennis was one of the original Olympic sports, and has been consistently competed in the Summer Olympic Games since 1988.

White is the lightest color and is achromatic (having no chroma). It is the color of objects such as snow, chalk, and milk, and is the opposite of black. White objects fully reflect and scatter all the visible wavelengths of light. White on television and computer screens is created by a mixture of red, blue, and green light. The color white can be given with white pigments, especially titanium dioxide.

In ancient Egypt and ancient Rome, priestesses wore white as a symbol of purity, and Romans wore white togas as symbols of citizenship. In the Middle Ages and Renaissance a white unicorn symbolized chastity, and a white lamb sacrifice and purity. It was the royal color of the kings of France as well as the flag of monachist France from 1815 to 1830, and of the monarchist movement that opposed the Bolsheviks during the Russian Civil War (1917–1922). Greek temples and Roman temples were faced with white marble, and beginning in the 18th century, with the advent of neoclassical architecture, white became the most common color of new churches, capitols, and other government buildings, especially in the United States. It was also widely used in 20th century modern architecture as a symbol of modernity and simplicity.

According to surveys in Europe and the United States, white is the color most often associated with perfection, the good, honesty, cleanliness, the beginning, the new, neutrality, and exactitude. White is an important color for almost all world religions. The pope, the head of the Roman Catholic Church, has worn white since 1566, as a symbol of purity and sacrifice. In Islam, and in the Shinto religion of Japan, it is worn by pilgrims. In Western cultures and in Japan, white is the most common color for wedding dresses, symbolizing purity and virginity. In many Asian cultures, white is also the color of mourning.