If I put my laptop on my lap and block the air vents, wouldn't this be bad for the computer?

Yes.

I am no expert but I would little props under it. You know four, so it is raised.

Blocking the vents will increase the heat, despite being designed to be used on the lap, but the computer won’t overheat. It will usually consume a lot of fan power when you ware watching videos or playing games because you are utilizing a lot of processing power. If you are concerned that the laptop may become damaged due to heat, perhaps you should purchase a laptop desk for your lap. Note Laptops are known to shutdown automatically if they record a level of heat higher than normal. A safety precaution if we may. Cheers!

Yes. Even with proper cooling air circulation, your laptop is already cooking itself to an early death because the componants are all crammed into a small space around the processor.

Yes! It really does :)

You are doing the right thing. The air vents are critically important. I keep a stiff plastic tray in my case so I can place my laptop on it when I use it on my bed or lap.

Definitively bad, yeah.

Most “laptops” are actually called “notebook computers” to get around this technicality. Yes blocking the vents is bad, my mates laptop full on exploded smoke and all when he left it on his duvet cover running. I seriously would not recommend it. When I am at home I use a bean bag lap tray to put my laptop on to stop the vents getting covered. Macs are great as they have no vents underneath with the only vent being along the back where the screen is. They are true laptops but most people (me included) can not afford luxuries such as a mac!
If it is more of an “on the move” problem with wanting to put your laptop on your lap I tend to use a stiff ring-binder as these are also angled so they are easier to use when on your lap or I actually used to take one of those really thin plastic tray out in my laptop bag as my old laptop had lots of overheating tenancies.

I don’t know how common this is, but my sister got a bad burn on her leg from falling asleep with a laptop on her lap. Granted, she had taken a sleeping pill before this happened, but anything that can leave burns like that on your leg is probably something you should be careful with. They make trays for the laptops to sit on your lap without blocking any vents or heating up your skin. Some even have a cup holder. Pretty cool. :)

I have a lap-sized pillow that has a fairly loose composition between my laptop and my lap. When I say “loose composition”, I mean that someone would have to try really hard to suffocate me with this thing (line forms to the rear, folks, no shoving, please, everyone can have a chance) because it’s pretty breathable.

This way both the computer and my lap get a break from the heat. But it also helps that my machine has its air vents in the back edge. (I wonder why more notebook / laptop computers don’t do that.)

I use a little folding laptop tray with mouse pad that keeps the laptop stable and allows for air circulation. Even just putting it on something flat such as a notebook allows for more air circulation than it would get directly on your relatively soft and gently contoured lap.

I had to buy a laptop fan to put under the computer on my lap. Mine kept shutting down when it got hot.

If by “bad” you mean “cause it to overheat, dramatically shorten the battery life, possibly melt solder joints, and maybe even cause injury and/or ignite”, then yes.

While it’s true that the computer will shut down at a certain temperature, it’s also true that long-term exposure to a low-level overheat can cause as much damage as the sort of temperatures that the thermal cutoffs are designed to protect from. Put another way, holding your hand in a pot of boiling water won’t hurt you as bad as a welding torch, but it will still hurt.

Also note that Lithium batteries do not like high temperatures. The hotter your laptop runs, the warmer the battery gets. The warmer the battery gets, the quicker it will die permanently. Normally, they lose ~15% of their capacity per year; at higher temps (like those next to an overheating CPU) it’s often double that (-30%/yr).

Thing is, the vents on a properly designed laptop like my Toshiba are someplace where they really cannot be blocked; the left edge (on the side, not the bottom) and in the center of the bottom between my thighs. And for those that are not as well-designed, there are cooling trays.

@CWOTUS I think it’s because they are stupid. It would seem to me that lacking edge-mounted vents borders on moronic unless you somehow design in alternative cooling like Apple did by using the entire aluminum case as a heatsink or use a low-powered CPU that barely generates any heat anyways.

@bongo I could be wrong, but I think that may have started back in the Pentium III days when, due to a combination of less evolved technology and the occasional use of desktop CPUs in portable systems, “laptops” ran at temperatures that would literally scorch flesh. As class action lawsuits for injuries tend to be pricey, it was cheaper for computer makers to change the name, advise against actual lap-based use, then deny responsibility for using the product in unintended ways than it was to just keep on calling them “laptops”.

As others have said, yes. Given their compact design, a notebook must have adequate circulation, even if that means that it’s on a simple flat surface.

Wow! The advice is unanimous on this one!
@bongo The ring binder is a great idea.
I’m also going to buy one of those cooling pads with a fan in them, like the one @YARNLADY suggests.
Thank you, everybody.