Full binary trees, Complete binary trees and perfect binary trees

[Gaiety]

can some one please discuss the types of binary trees?
especially full binary trees , perfect binary trees and complete binary trees.
all these definitions looks same.
where actually these are used?

thanks,
Gaiety

[Tom Gunn]

Complete Binary Tree , Full Binary Tree , Perfect Binary Tree .

According to those definitions, I would draw the difference like this:

// Trees rotated 90 degrees counter clockwise

Perfect:       Full:         Complete:

      g              e
   c              c             c
      f              d

a              a             a

      e                            e
   b              b             b
      d                            d

The perfect tree is completely filled, the full tree is a perfect tree where the bottom level is partially filled, and the complete tree is a full tree where the bottom level has to be left oriented.