2021 Topps 206 Baseball – Wave 7

2021 (MMXXI) was a common year starting on Friday of the Gregorian calendar, the 2021st year of the Common Era (CE) and Anno Domini (AD) designations, the 21st year of the 3rd millennium and the 21st century, and the 2nd year of the 2020s decade.

Like the year 2020, 2021 was also heavily defined by the COVID-19 pandemic, due to the emergence of multiple COVID-19 variants. The major global rollout of COVID-19 vaccines, which began at the end of 2020, continued in 2021. Most major events scheduled for 2020 that were postponed due to the pandemic were hosted in 2021, including the 26th United Nations Climate Change Conference, Expo 2020, and sporting events such as UEFA Euro 2020, the 2020 Summer Olympics and Paralympics, as well as the 2021 Copa América.

2021 additionally witnessed numerous advancements in space exploration, particularly by the United Arab Emirates, NASA and SpaceX, including the launch of the James Webb Space Telescope.

Civil unrest grew in 2021, with coups occurring in Sudan, Myanmar, Mali and Guinea, and insurrections occurring in Armenia and the United States.

Year 206 (CCVI) was a common year starting on Wednesday of the Julian calendar. At the time, it was known as the Year of the Consulship of Umbrius and Gavius (or, less frequently, year 959 Ab urbe condita). The denomination 206 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.

7 (seven) is the natural number following 6 and preceding 8. It is the only prime number preceding a cube.

As an early prime number in the series of positive integers, the number seven has symbolic associations in religion, mythology, superstition and philosophy. The seven classical planets resulted in seven being the number of days in a week. 7 is often considered lucky in Western culture and is often seen as highly symbolic.

Baseball is a bat-and-ball sport played between two teams of nine players each, taking turns batting and fielding. The game occurs over the course of several plays, with each play beginning when a player on the fielding team, called the pitcher, throws a ball that a player on the batting team, called the batter, tries to hit with a bat. The objective of the offensive team (batting team) is to hit the ball into the field of play, away from the other team's players, allowing its players to run the bases, having them advance counter-clockwise around four bases to score what are called "runs". The objective of the defensive team (referred to as the fielding team) is to prevent batters from becoming runners, and to prevent runners advancing around the bases. A run is scored when a runner legally advances around the bases in order and touches home plate (the place where the player started as a batter).

The initial objective of the batting team is to have a player reach first base safely; this occurs either when the batter hits the ball and reaches first base before an opponent retrieves the ball and touches the base, or when the pitcher persists in throwing the ball out of the batter's reach. Players on the batting team who reach first base without being called "out" can attempt to advance to subsequent bases as a runner, either immediately or during teammates' turns batting. The fielding team tries to prevent runs by using the ball to get batters or runners "out", which forces them out of the field of play. The pitcher can get the batter out by throwing three pitches which result in strikes, while fielders can get the batter out by catching a batted ball before it touches the ground, and can get a runner out by tagging them with the ball while the runner is not touching a base.

The opposing teams switch back and forth between batting and fielding; the batting team's turn to bat is over once the fielding team records three outs. One turn batting for each team constitutes an inning. A game is usually composed of nine innings, and the team with the greater number of runs at the end of the game wins. Most games end after the ninth inning, but if scores are tied at that point, extra innings are usually played. Baseball has no game clock, though some competitions feature pace-of-play regulations such as the pitch clock to shorten game time.

Baseball evolved from older bat-and-ball games already being played in England by the mid-18th century. This game was brought by immigrants to North America, where the modern version developed. Baseball's American origins, as well as its reputation as a source of escapism during troubled points in American history such as the American Civil War and the Great Depression, have led the sport to receive the moniker of "America's Pastime"; since the late 19th century, it has been unofficially recognized as the national sport of the United States, though in modern times is considered less popular than other sports, such as American football. In addition to North America, baseball spread throughout the rest of the Americas and the Asia–Pacific in the 19th and 20th centuries, and is now considered the most popular sport in parts of Central and South America, the Caribbean, and East Asia, particularly in Japan, South Korea, and Taiwan.

In Major League Baseball (MLB), the highest level of professional baseball in the United States and Canada, teams are divided into the National League (NL) and American League (AL), each with three divisions: East, West, and Central. The MLB champion is determined by playoffs that culminate in the World Series. The top level of play is similarly split in Japan between the Central and Pacific Leagues and in Cuba between the West League and East League. The World Baseball Classic, organized by the World Baseball Softball Confederation, is the major international competition of the sport and attracts the top national teams from around the world. Baseball was played at the Olympic Games from 1992 to 2008, and was reinstated on a one-off basis in 2020.

The Topps Company, Inc. is an American company that manufactures trading cards and other collectibles. Formerly based in New York City, Topps is best known as a leading producer of baseball and other sports and non-sports themed trading cards. Topps also produces cards under the brand names Allen & Ginter and Bowman.

In the 2010s, Topps was the only baseball card manufacturer with a license with Major League Baseball. Following the loss of that license to Fanatics, Inc. in 2022, Fanatics acquired Topps in the same year.

In physics, mathematics, engineering, and related fields, a wave is a propagating dynamic disturbance (change from equilibrium) of one or more quantities. Periodic waves oscillate repeatedly about an equilibrium (resting) value at some frequency. When the entire waveform moves in one direction, it is said to be a travelling wave; by contrast, a pair of superimposed periodic waves traveling in opposite directions makes a standing wave. In a standing wave, the amplitude of vibration has nulls at some positions where the wave amplitude appears smaller or even zero.

There are two types of waves that are most commonly studied in classical physics: mechanical waves and electromagnetic waves. In a mechanical wave, stress and strain fields oscillate about a mechanical equilibrium. A mechanical wave is a local deformation (strain) in some physical medium that propagates from particle to particle by creating local stresses that cause strain in neighboring particles too. For example, sound waves are variations of the local pressure and particle motion that propagate through the medium. Other examples of mechanical waves are seismic waves, gravity waves, surface waves and string vibrations. In an electromagnetic wave (such as light), coupling between the electric and magnetic fields sustains propagation of waves involving these fields according to Maxwell's equations. Electromagnetic waves can travel through a vacuum and through some dielectric media (at wavelengths where they are considered transparent). Electromagnetic waves, as determined by their frequencies (or wavelengths), have more specific designations including radio waves, infrared radiation, terahertz waves, visible light, ultraviolet radiation, X-rays and gamma rays.

Other types of waves include gravitational waves, which are disturbances in spacetime that propagate according to general relativity; heat diffusion waves; plasma waves that combine mechanical deformations and electromagnetic fields; reaction–diffusion waves, such as in the Belousov–Zhabotinsky reaction; and many more. Mechanical and electromagnetic waves transfer energy, momentum, and information, but they do not transfer particles in the medium. In mathematics and electronics waves are studied as signals. On the other hand, some waves have envelopes which do not move at all such as standing waves (which are fundamental to music) and hydraulic jumps.

A physical wave field is almost always confined to some finite region of space, called its domain. For example, the seismic waves generated by earthquakes are significant only in the interior and surface of the planet, so they can be ignored outside it. However, waves with infinite domain, that extend over the whole space, are commonly studied in mathematics, and are very valuable tools for understanding physical waves in finite domains.

A plane wave is an important mathematical idealization where the disturbance is identical along any (infinite) plane normal to a specific direction of travel. Mathematically, the simplest wave is a sinusoidal plane wave in which at any point the field experiences simple harmonic motion at one frequency. In linear media, complicated waves can generally be decomposed as the sum of many sinusoidal plane waves having different directions of propagation and/or different frequencies. A plane wave is classified as a transverse wave if the field disturbance at each point is described by a vector perpendicular to the direction of propagation (also the direction of energy transfer); or longitudinal wave if those vectors are aligned with the propagation direction. Mechanical waves include both transverse and longitudinal waves; on the other hand electromagnetic plane waves are strictly transverse while sound waves in fluids (such as air) can only be longitudinal. That physical direction of an oscillating field relative to the propagation direction is also referred to as the wave's polarization, which can be an important attribute.