I was all ways a big fan of stuff like this but I still dont get it. Is this like a nation makes there own message board then that nation get's invaded by a spam attack or what?
You're going to have to rephrase that - we don't understand what you mean.
Oh. He's asking what an "invasion" techincally is. An "Invasion" is when nations from another region join another region, and something along the lines "attack" the region, until it becomes part of the "empire" of the "attacking" region. It's primarily for roleplay purposes, and I do not believe it directly affects main gameplay in any way shape or form.