Role

In Dota 2, roles define the way a hero can be played given their Attributes, Skills, and Items. Different heroes are suited for different roles and can be played in a variety of ways based on a player's preference and the team's composition. It is important to know how to effectively play a hero in many roles, as this increases the flexibility of your team, especially in a competitive draft setting. There are three primary roles: Carry, Semi-Carry, and Support. In addition to a hero's primary role, he may or may not belong to a secondary role: Ganker, Pusher, Tank, Jungler, and Initiator.

Primary Roles
All heroes fall into one of three primary roles based on their purpose in the team. Typically, a team is composed of one Carry and one to three Semi-Carries, with the remainder of the team being Supports.

Carry
Also known as a "Hard(core) Carry" (as opposed to a "Semi-Carry"), a Carry is the hero that a team rallies around late game. (The role's name is derived from the act of "carrying" a team; that is, to bear the responsibility for ultimate victory.) Carries typically lack early game power, but they have strong scaling skills; thus, they are highly dependent on items in order to be successful. Having more than one Carry will cause competition within your team for resources, which typically results in a number of underpowered Carries. It is highly recommended that a team have only one Carry.

Carries typically are relegated to a side lane early on with one or more Support heroes to babysit them until they collect the necessary items to farm independently.


 * Examples: Anti-Mage,  Sniper,  Spectre,  Drow Ranger.

Semi-Carry
Semi-Carries are heroes with strong early or middle game power that drop off later in the game. These heroes are not as item dependent as a typical Carry and can function with a few core items. Furthermore, because of their lack of item dependence, Semi-Carries often purchase utility items. Early on, the Semi-Carries typically take the lead in asserting map control to allow the Carry to farm. They transition later on into a more supportive role.

A Semi-Carry always takes the middle lane, allowing him access to both side lanes. A team typically has multiple Semi-Carries, depending on the laning strategy. If there is a Jungler, expect to see a Semi-Carry solo in the long lane (bottom for Radiant and top for Dire).


 * Examples: Windrunner,  Necrolyte,  Tinker,  Invoker.

Support
Supports are heroes whose purpose are to keep their allies alive and give them opportunities to earn more gold and experience. Supports will usually come with skills such as healing spells or skills that disable enemies. Like Semi-Carries, Supports are not dependent on items, and thus, most of their gold will be spent on items such as Animal Courier, Observer Ward, Sentry Ward, and Smoke of Deceit.

Supports are typically paired with the team's Carry at the start of a game. This is because the Carry tends to be the weakest and most gold-hungry member of the team early on.


 * Examples: Lich,  Dazzle,  Crystal Maiden,  Omniknight.

Secondary Roles
Secondary roles are sub-classes of the primary roles and may or may not be present on your team.

Ganker
Gankers, also known as "Roamers", are heroes with high mobility (or range) and strong early game damage output. Their goal is to give the team an early game advantage by killing enemy heroes, as well as to roam the enemy jungle to stop enemy Carries from farming properly.


 * Examples: Clinkz,  Bounty Hunter,  Nature's Prophet,  Chen,  Batrider,  Night Stalker.

Initiator
Initiators are heroes who can safely and advantageously start a team fight. These heroes typically have strong area of effect damage or disable or some skill to affect the positioning of the enemy team. Although it is common for an Initiator to be a Tank, this is not always the case; heroes such as Vengeful Spirit can attempt a "suicide swap" to isolate and quickly eliminate an enemy Carry.


 * Examples: Tidehunter,  Earthshaker,  Axe,  Puck,  Clockwerk,  Pudge,  Vengeful Spirit.

Pusher
Pushers are heroes who focus on bringing down towers, thereby acquiring map control. If they succeed, they often shut down the enemy carry by forcing them away from farming. They typically have skills that fortify allied creep waves, summon minions, or deal massive amounts of damage to enemy towers.


 * Examples: Nature's Prophet,  Broodmother,  Shadow Shaman,  Pugna.

Jungler
Junglers are heroes that jungle neutrals at the start of the game, rather than lane. This allows for there to be two solo lanes. Junglers typically have skills that allow them to convert neutral creeps, summon minions, or sustain themselves through damage.

It is important to note that although having two solo lanes and a Jungler produces a significant gold and experience advantage, it increases exposure to enemy ganks. To alleviate this, make sure your second solo hero is a Semi-Carry in the long lane (bottom for Radiant and top for Dire). This way, the creeps fight closer to the tower and the Jungler can quickly come to his aid or gank; there is a reason why this lane is called the "safe lane" and the other side lane the "suicide lane".


 * Examples: Nature's Prophet,  Axe,  Lycanthrope,  Enigma.

Tank
Tanks are heroes with insane amounts of HP, HP regeneration, and armor. Thus, they can take high amounts of damage. However, the cost of this bulkiness is reduced damage per second. Typically, Tanks fill other secondary roles, usually Initiator. As most heroes have no true way to force enemies to attack them (Axe being the sole exception), most use their disables to peel for their carries.


 * Examples: Centaur Warchief,  Pudge,  Axe,  Medusa.