When an exit statement is reached the flow of control is terminated, and the method is exited to the calling method. If this occurs in the main block, then the program terminates without error.

var
   loop:longint;

begin
   for loop:=1 to 100 do begin
      if loop=50 then exit;
      writeln(loop);
   end;
end;

Will output 1 to 49, as the loop it broken when loop equals 50.

Source: Reserved Words

See Also:

continue, break, for, repeat, while.