Generally, a battle is a conceptual component in the hierarchy of combat in warfare between two or more armed forces, or combatants. In a battle, each combatant will seek to defeat the others, with defeat determined by the conditions of a military campaign. Battles generally are well defined in duration, area and force commitment.

Wars and military campaigns are guided by strategy, whereas battles take place on a level of planning and execution known as operational mobility. German strategist Carl von Clausewitz stated that "the employment of battles ... to achieve the object of war" was the essence of strategy.

The definition of a battle cannot be arrived at solely through the names of historical battles, many of which are misnomers. The word battle is a loanword in English from the Old French bataille, first attested in 1297, from Late Latin battualia, meaning "exercise of soldiers and gladiators in fighting and fencing", from Late Latin (taken from Germanic) battuere "beat", from which the English word battery is also derived via Middle English batri, and comes from the staged battles in the Colosseum in Rome that may have numbered 10,000 individuals.

An arena is an enclosed area, often circular or oval-shaped, designed to showcase theater, musical performances, or sporting events. The word derives from Latin harena, a particularly fine/smooth sand used to absorb blood in ancient arenas like the Colosseum in Rome. It is composed of a large open space surrounded on most or all sides by tiered seating for spectators. The key feature of an arena is that the event space is the lowest point, allowing for maximum visibility. Usually, an arena is designed to accommodate a fairly large number of spectators.

The term arena is sometimes used as a synonym for a very large venue such as Pasadena's Rose Bowl, but such a facility is typically called a stadium, especially if it does not have a roof.^{[citation needed]} The use of one term over the other has mostly to do with the type of event. Football (be it association, rugby, or gridiron) is typically played in a stadium while basketball and ice hockey are typically played in an arena, although many of the larger arenas hold more spectators than do the stadiums of smaller colleges or high schools. There are exceptions. The home of the Duke University basketball team would qualify as an arena, but the facility is called Cameron Indoor Stadium. Domed stadiums, which like arenas are enclosed but have the larger playing surfaces and seating capacities found in stadiums, also fall under a gray area. There is also the sport of indoor American football (one variant of which is explicitly known as arena football), a variant of the gridiron-based game that is designed for the usual smaller playing surface of most arenas; variants of other traditionally outdoor sports, including box lacrosse and futsal/indoor soccer, also exist.