It has a number of different names, astral projection, spirit walking, remote viewing, etc. It probably happens to everyone by those who know such techniques, but as I'm learned myself I can see when I get visitors. Usually they are just curious strangers from the internet who might have seen a post of mine relating to spiritual stuff. Curious and nosy
I usually ask them to leave, because, you know, they're uninvited. And I like to keep my space clean.