Which one should you pick? It depends on the laptop and on what you ask of it. A fanless MacBook Air or any thin, low-power machine is fine closed all day, and you can even buy stands made for exactly that. If you're running a gaming laptop or any workstation that gets properly hot, leave it open. And if you're unsure, check the manufacturer's site to see whether it's happy running under load with the lid shut.

If you go closed, there are a few things worth doing. Keep the power adapter plugged in, since the laptop draws more power with an external monitor attached, and you don't want the battery draining quietly in the background. In Windows, open Control Panel and look for Choose what closing the lid does, then set both lid options to Do nothing, or the laptop will go to sleep the second you shut it. Put it on a stand so air can get under it, and don't count on a cooling pad to do much; those only lower temperatures a little and don't cool the gap between the screen and the body.

There's also a middle road. Close the lid just far enough to switch the screen off, but not all the way, and as long as hot air isn't blowing straight onto the display, it should be fine indefinitely. It won't keep the dust out, though, so plan on cleaning the laptop every so often.

Overnight jobs are the easy case. A render, a big download or an old laptop acting as a home server can all run with the lid shut, as long as the vents are clear and the work is light to medium. Heavy loads are another story.

If you keep it open, the tips are simpler. Give the laptop some space so the air can move, keep the vents clear and, if it's a gaming laptop, tilt it up on a stand.

One tip works for both approaches: Get a docking station. A good one takes the keyboard, mouse, network cable, HDMI and audio out, so the laptop only needs one cable to connect to all of it. When you want to take the laptop somewhere, you unplug that one cable and go, instead of pulling five. Most also hold the laptop tilted, so there's room for air to get around it.