What do you consider cheating?

I want to know what do you consider cheating? Do you think cheating is when you talking to someone else on the phone or internet knowing that you have a gf or bf, but you are only conversating you have established that it's not going to go beyond friendship. Do you think that is cheating? What about going to the guy or girls house to chill out and talk? Of course by doing all of these you might develope feelings. I know that passing that friendship level like kissing and everything past kissing is cheating, but is talking on the phone and going to lead for grounds of cheating(even though I know that is not a word). So what do you think?