Personal space. I don't normally have a personally space issue. I don't care if people sit close to me or stand too close. Hopefully not within spitting distance.
I do think there is a natural distance one should sit or stand from another person but when people are friends I may sit closer. If I am ill I stand even farther away.
When I am sick I try not to cough in elevators or sneeze in groups. If others are ill I hope they will do the same.
Recently I have had this situation with someone who repeatedly puts her stuff in my area whether I am sitting there or not. I will be working and she will put her coffee mug on my workspace because she doesn't want to accidentally knock it over on her workspace. I will arrive to work and her papers will be strewn all over my designated workspace and her coat on the chair.
I try to give subtle hints like walking in and saying "look at all this stuff in my work area!" and I move it and move her coat. Today she wanted to put her big binder on my work space and I said no. But I know next time I show up it will be there.
What would you do with someone who moves in on a space that is designated as yours?