Association uses-a · plain line
Driver
whole
Car
part
Driver knows a Car. Neither owns the other.
Aggregation has-a · hollow ◇
Team
whole ◇
◇————
free pool — players that exist on their own
(empty)
Team has shared Players. They can outlive the team.
Composition owns-a · filled ◆
House ◆————
House owns its Rooms. They're built inside it.
console
Ask one question: what happens to the part when the whole is destroyed? The car lives, the players escape, the rooms die.