Trade is the transfer of ownership of goods and services from one person or entity to another by getting something in exchange from the buyer. Trade is sometimes loosely called commerce or financial transaction or barter. A network that allows trade is called a market. The original form of trade was barter, the direct exchange of goods and services. Later one side of the barter were the metals, precious metals (poles, coins), bill, paper money. Modern traders instead generally negotiate through a medium of exchange, such as money. As a result, buying can be separated from selling, or earning. The invention of money (and later credit, paper money and non-physical money) greatly simplified and promoted trade. Trade between two traders is called bilateral trade, while trade between more than two traders is called multilateral trade.

Trade exists for man due to specialization and division of labor, most people concentrate on a small aspect of production, trading for other products. Trade exists between regions because different regions have a comparative advantage in the production of some tradable commodity, or because different regions' size allows for the benefits of mass production. As such, trade at market prices between locations benefits both locations.

DeMarcus Cousins (born August 13, 1990) is an American professional basketball player with the Sacramento Kings of the National Basketball Association. He played college basketball at the University of Kentucky.

Cousins was named to the 2009 McDonald's All-American Team. He had 14 points and 8 rebounds. Cousins also played in the 2009 Nike Hoop Summit at the Rose Garden in Portland and the Jordan Brand Classic at Madison Square Garden where he scored 10 points for the black team. Cousins led LeFlore to the Alabama class 6A Final Four against Hillcrest that beat Austin High School to progress to the state championship; falling short to future college teammate Eric Bledsoe and Parker High School.

Cousins first committed to Alabama-Birmingham on February 28, 2008 but never signed a letter of intent because he wanted to be released if UAB's head coach, Mike Davis, left for another school. Cousins decomitted from UAB and committed to Memphis on March 9, 2009. He reopened his recruitment after then Memphis coach John Calipari was hired at Kentucky. On April 7, 2009, Cousins decided to follow John Calipari to Kentucky. He signed his Letter of Intent on April 15. At Kentucky, Cousins averaged 15.1 points, 9.8 rebounds and 1.8 blocks per game. Led by Cousins and John Wall, the Wildcats reached the Elite Eight of the 2010 NCAA Tournament.

Rajon Pierre Rondo (born February 22, 1986) is an American professional basketball point guard with the Boston Celtics of the National Basketball Association (NBA). Born in Louisville, Kentucky, Rondo attended Eastern High School and Oak Hill Academy for his high-school basketball career, before receiving a scholarship from the University of Kentucky. He played for two years at Kentucky before declaring for the 2006 NBA Draft, represented by agent Bill Duffy.

During the draft, Rondo was selected 21st overall by the Phoenix Suns, and was subsequently traded to the Boston Celtics, where he made his NBA debut as a rookie during the 2006–07 season. He played a supporting role before he established himself as the starting point guard for the Celtics during the 2007–08 season. That season, Rondo earned his first NBA Championship, playing alongside All-Stars Kevin Garnett, Ray Allen and Paul Pierce. His breakout performance came during the 2009 NBA Playoffs, where he nearly averaged a triple-double, and helped his team take the eventual Eastern-conference champion Orlando Magic seven games in the Eastern semi-finals. He ranks eighth in Celtics history in assists and fifth in steals.