Bot lane.
It's the bottom lane as it says it's name, in this lane, are played two champs/players.
Support and AD carry, a support champ it's usually used to protect it's adc, and sometimes the other players. They care about vision too, they put wards on the ''rift'' which are used to have vision and see what the enemy team is doing.
An adc it's usually a marksman. BUT THEN OUR LOVELY RIOT, PUTS MORDEKAISER LIKE AN ADC WITH NO FKING SENSE AND WE NEED TO INSTA BAN HIM BECAUSE IT'S BROKEN. -Rage quit.- hahaha, okay no. He's principal function it's to farm, and farm..and..farm?
Today I'm so funny, sorry. (irony)
They do the most part of the damage too, like the Mid laners, they only have to stay back in the team fights or stay protected by their supports, if they don't do that or they die the first, there would be no damage, and the team fight will be probably lost.