The battle for overhead bins is raging. These are the rules to play by.

You know, the travelers who stuff everything they lugged onto the plane into the overhead bin as if they own it. Or the people who go all “Tetris" on your stuff to squeeze their bag in. And let’s not forget the passengers who willfully ignore the reserved signs and plop their bags in the first-class or economy-plus bins.

These overhead bin offenses eat up precious bin space, clog boarding and can lead to a dreaded gate-checked bag. Not to mention that they annoy fellow passengers. Flight attendants keep an eye on things but don’t have time to monitor every bin.

It all calls for a refresher on overhead bin basics and etiquette. I mean, this column is called Carry On, after all.

Let’s start by setting expectations. Your seat is assigned (on every major U.S. airline but Southwest) but bin space isn’t, at least in regular economy. It’s shared space and may or may not be available depending on when you board.

Rich and Drew Henderson are married flight attendants from Philadelphia who run the Two Guys on a Plane Instagram account and are about to launch a podcast. They had seen enough confusion around bins to post a reminder just before the year-end holidays.

Rich Henderson says it was prompted by a passenger who was steamed after boarding only to find no room in the bin above their row. “People have this idea in their head that the space directly above their seat is theirs and they own it," he says.

That isn’t true, even in premium cabins, though first class is generally policed more than other extra-legroom sections.

Mind your manners

So here are some reminders on how to behave. First, don’t be selfish, even if no one is looking.

The rule on most airlines is to put your larger carry-on in the overhead bin and the smaller personal item under your seat. Alaska Airlines recently introduced video messages at the gate illustrating this simple concept.

If you aren’t a frequent flier, pay close attention to signs and announcements on how to place those carry-on bags in the bin. More and more planes have bigger bins; they only hold more bags if you place them on their side. Airline verbiage on what that means varies: Some say stack bags like books on a shelf, others like a hard-shell taco. But you get the point.

Don’t move someone else’s stuff without care and, when possible, asking if it’s OK. It sounds unfathomable but one traveler reports that a fellow passenger removed her CPAP machine from the overhead bin last summer to make room for a bag.

Another way to be considerate to fellow passengers: Get your essentials out of your carry-on bag before you stow it.

Virginia management consultant Bill Huber doesn’t get rattled by much when he travels. But the 6-foot-3 aisle-seat fan gets irritated when passengers repeatedly go to the bin, during boarding or after takeoff, for items like headphones, chargers, snacks or tablets. He recommends tucking them into a smaller bag before boarding.

Bill Huber and his wife, Lynn Huber, in front of the New York Public Library’s Main Branch on Fifth Avenue.

“It’s smart and just takes a tiny bit of planning," he says. “It makes everyone more comfortable."

Rich Henderson says the up-and-down passengers slow boarding even more than overhead-bin hogs.

The minimalists

There is one group of travelers who take particular issue with travelers who think only big bags belong in the overhead bin. These minimalist travelers only carry a backpack. On Reddit, they are disciples of what is called one-bagging.

They take offense when other travelers or flight attendants ask them to put their backpacks, their only carry-on, underneath the seat to accommodate another passenger’s bigger carry-on.

It happened to Nick Ridgeway, 33, on an Allegiant flight from Las Vegas to Grand Island, Neb., last summer on the way home from a friend’s wedding. The Nebraska attorney says he was asked to take his 38-liter backpack out of the overhead bin.

Nick Ridgeway with his daughter, Abigail Ridgeway, and the backpack he takes aboard airplanes.

That meant a long fight with the backpack at his feet even though he paid a hefty fee to bring on a traditional carry-on, a common practice at budget airlines. Ridgeway says he started to politely argue with the flight attendant but didn’t want to get kicked off the flight like Ben Stiller in “Meet the Parents."

“I’m absolutely just stewing in my juices," he says. The flight attendant eventually found another spot for his bag.

You don’t have to be a light packer to feel unfairly shut out of the overhead bin. Travelers who pay to check a bag or offer to gate-check it for free say it isn’t fair to be asked to put their small backpack under their feet.

A Threads post last week by a Delta Air Lines passenger who brought a single item on board and was asked to move it out of the overhead bin to his feet drew hundreds of sympathetic responses.

“I paid to check my bag, and for my extra legroom, and now I have to suffer because someone tries to fit three weeks worth of crap in the overhead?" one traveler said.

The bottom line: There isn’t enough space in the overhead bins for all of our carry-on bags, no matter the size. So take your share and nothing more.

“It’s a tight space," Drew Henderson says. “We’re not all going to get what we want out of this."

Write to Dawn Gilbertson at dawn.gilbertson@wsj.com