If you're doing ballroom dancing, you will meet the term "line of dance." The progressive dances, such as waltz, foxtrot and quickstep, go round and round the room counter-clockwise. Obviously, dancing against line of dance is a bad thing on a crowded floor, as you will be running against traffic. Faster-moving dancers generally take the outside line while slower-moving dancers stay closer to the middle of the floor; so the faster you dance, the bigger the radius of the circle you make around the floor.
Some songs are suitable for dancing both a progressive and a non-progressive dance; something fast in 4/4 time may work for both quickstep (progressive) and swing/jive (non-progressive). Dance floor etiquette is for people doing swing to stay in the MIDDLE of the room, so the progressive dancers can go round the outside. Swing dancers on the outside of the room are a traffic hazard as progressive dancers have to dodge them.
It's common for people who feel nervous or uncertain, or who don't want to show off, to feel that they should stay on the outskirts of the room. This is counter-productive; staying on the outskirts puts you in traffic, plus you'll be close to a wall or the edge of the floor. Safety, anonymity and free space lie in the middle of the floor.
So when we quickstep, swing dancers PLEASE stay in the middle.
That's not so hard, is it?