A team is a group of people who have a certain task to complete. In order to meet their target, the members of the group must work well with each other.
Successful team - a group of people who tend to meet their target without facing any sort of barrier. The group members cooperate with each other and take other members' ideas into consideration.
Unsuccessful team - a group of people who have a very difficult time when attempting to complete a certain task. The members of the group think of only themselves and create an uncomfortable environment for other members of the team.