Dota 2/Roles

Like any multiplayer team-based game, each hero will usually have a role issued for him/her. A hero's role is the part the hero plays during a match. Some heroes are better at one role, while others can adapt to a lot of roles. Understanding the role of your own hero is key to winning a match.

Carry
The carry is a hero with the capability to carry the entire team to victory. These heroes are extremely dependent on farming and are usually relatively weak at the first half of the game. However, once they get enough gold and bought some powerful items, they can shred the entire enemy team. As a carry it is important to get as many last hits as you can, and try not to die so you don't lose your gold. One very VERY important rule for carries is that there should only be ONE carry on your team. A carry, as stated before, is very farm dependent, and multiple carries will have to compete with each other for gold and experience. At the end of the day, having too many carries will result in neither being exceptionally powerful.

Support
A support is obviously a hero that has good abilities to help his/her team. These heroes don't need to farm for items to be effective as they already have great innate abilities to help them perform effectively. A thing to remember as a support is to let the heroes that need more gold get last hits.