Question: What is a Gateway?

As in, a person who can not experience anything paranormal per se for themselves, but somehow act as a conduit for ghosts and other things, and something to do with emotions. I have tried researching what this is but can't seem to find anything, however, I have heard from multiple people who had nothing to do with each other take about Gateways and give similar information. I'm not content with just that little bit.

(Edit: added a word)