That depends on the thought process of who is defining the 'hacking'. To some (uninformed) people, running anything from the command line, or booting from a Linux CD, is 'hacking'.
'Gain unauthorized access to data in a system or computer' That's what I'm going by. (btw this isn't for me my friends are arguing about it)
If you are changing the content or design of a webpage in a way that is unauthorized by the owner, then yes....that would be 'hacking'. (If we are going by the current bastardized definition of 'hacking')