Spamming?

[saintlover]

I have seen alot of people referencing spamming in posts regarding harassment. What exactly considered spamming? I leave messages every day on my friends walls letting them know I was there on whatever day it is. There are some walls that my comments are the only one there for weeks at a time. I guess that "could" technically be considered spamming. For clarification, what exactly does TL's consider spam? Thanks.