Medium tanks are multi-purpose tanks with balanced characteristics that can assume many different roles in game. They are represented by a two-piece green or red diamond on the mini-map and over their respective target marker.
How a medium tank performs varies greatly from tank to tank, but in terms of size, firepower, maneuverability, and protection medium tanks generally fall between the larger, burlier heavy tanks and the smaller, nimbler light tanks. Medium tanks take many characteristics from both, albeit to lesser extremes. They tend to be fairly maneuverable which allows them to take position and quickly relocate in ways heavy tanks and slow tank destroyers can't. Medium tank guns are usually more potent than those on light tanks but usually come up short of heavy tank guns. Despite this, most medium tanks have the firepower necessary to reliably do damage to enemy heavy tanks of their tier. Medium tanks also have moderate amounts of armor - enough to protect them from weaker guns and poorly aimed shots, but not enough to allow them to engage most tanks in drawn out, head-to-head brawls. Many high-tier medium tanks represent some of the first main battle tanks, and usually have similar, well-rounded attributes.
Since medium tanks are multi-role vehicles, exactly how they're played depends on the situation. In most cases, medium tanks are most effective supporting friendly heavy tanks or other higher tier mediums. When using their speed to engage in flanking maneuvers, medium tanks can put effective fire into larger enemy vehicles without putting themselves at risk. A well coordinated pair or group of medium tanks working in tandem can easily take down much larger enemies while taking little to no damage themselves. Medium tanks can also take on the roles of other more specialized vehicles that are either critically damaged or already destroyed. Depending on the characteristics of the specific tank being used, a medium tank can use its limited armor and remaining hitpoints to brawl for a short amount of time, its speed to scout enemy vehicles, or its firepower to give supporting fire.
Variety and Examples
While most medium tanks share the same well-rounded, multi-use performance, some are more specialized than others. Tanks such as the Matilda and Sherman Jumbo are medium tanks only by definition, and effectively play like heavy tanks at their tiers. Others, such as the Panther and Leopard are superb in the sniping role, but are poorly protected from enemy fire themselves. In addition, some tanks such as the M7 and A-43 sacrifice armor and firepower for great speed and gun handling, and therefore behave more like large light tanks.