Although there are different types of top laners, generally speaking, teams will play with a 'Tank' champion - someone who can take a lot of damage before being eliminated. They are used to get into the middle of the opposing team, being the focal point, or trying to stun or attack the enemy ADC.
The distraction caused by the Tank champion enables the rest of the team with high attack damage to eliminate the players. The laning phase is incredibly important for this role as the player needs to be strong for the later game.