Please tell

Roster form is enlisting the elements in {  } and separating them by comma ,.In this form all the elements are written explicitely. For example the set of natural numbers less than or equal to 10  in roster form is { 1,2,3,4,5,6....10} 

Set builder form : The property describing the elements is stated. This form is used particularly in case of infinite sets.

 { 1,2,3,4,5,6....10} in set builder form is { x:x is a natural number ≤ 10}