when does a conversation becomes a gossip?

There's really a thin line dividing this two, as discussions emit reactions and chances of passing the info down to more lines of communication which is also same with gossips. But one thing that differentiate the two is that in discussions nothing is harm, no reputation is being damage and all are for healthy discussions whereas in gossips name, reputations and family can be ruined and damaged. We are all doing discussions here but no gossips!

I think I draw the line the minute the conversation starts becoming about a particular person. I think that it's a waste of time to talk about someone else behind their backs because how is that benefiting me.

For me a conversation becomes a gossip, when it starts to delve on lives of others. As much as possible, we avoid conversations that talk about others specially when it's for the detriment of that person.