According to the Intel manual for developers, these instructions provide machine-language support for procedure calls in block-structured languages; however, they are very useful for Assembly developers as well.

When we implement a procedure, we have to take care of the creation of the stack frame where we store the procedure's variables, storing the value of ESP and then restoring all that before we leave a procedure. These two instructions can do all that work for us:

; Do something here
call   my_proc
; Do something else here

my_proc:
   enter 0x10, 0   ; Save EBP register on stack,
                   ; save ESP to EBP and
                   ; allocate 16 bytes on stack for procedure variables
   ;
   ; procedure body
   ;
   leave           ; Restore ESP and EBP registers (this automatically
                   ; releases the space allocated on stack with ENTER)
   ret             ; Return from procedure

The preceding code is equivalent to the following code:

; Do something here
call   my_proc
; Do something else here

my_proc:
   push   ebp       ; Save EBP register on stack,
   mov    ebp, esp  ; save ESP to EBP and
   sub    esp, 0x10 ; allocate 16 bytes on stack for procedure variables
   ;
   ; procedure body
   ;
   mov    esp, ebp  ; Restore ESP and EBP registers (this automatically
   pop    ebp       ; releases the space allocated on stack with ENTER)
   ret              ; Return from procedure