Collections lie in java.util package

• ArrayList and LinkedList extend List Interface.
• And List extends Collection
• Other than ArrayList and LinkedList we can use HashSet and LinkedHashSet
• Basically List , Set ,Queue and DeQueue extends Collection
• Another thing to note is for ArrayList ,LinkedList and LinkedHashSet items appear in order in which they were added .In HashSet they are not in order.
• Also note in Sets we can't add duplicate items.