Also known as stack buffer overflow, the goal is to overflow the stack to affect its memory (the mem that would normally be out of range/not changeable like a return address). This was rendered mostly useless (at least in its basic form) because we can now declare the buffer as non-executable and avoid the whole fiasco. ^[1]

#Stack Smashing Big brother, the goal is now to use that buffer to trick the process into returning data by using one of the process/library own instruction.^[2]