There are two types of memory volatile and non-volatile. Volatile means that it gets erased if it loses power and non-volatile means it stays if it loses power.

When your computer loads a program it loads it into volatile memory as it's a lot faster to access and make changes to. However, because it's making changes to it, it might do something weird that causes the program to mess up to either that specific program or something else that interacts with it.

By "turning it off and on again" you reset all of the volatile memory and reset it to its initial state, before it caused that issue for itself.

Because computers a really good at following instructions. They love following steps. But if something goes wrong and they get off of those steps it’s very hard for them to find their way back into them. But if you force the computer to start over at the beginning, chances are it will complete the steps just find as long as nothing goes wrong.

So turning something on and off again is essentially just saying “hey, you messed something up but you can do this, I’m gonna put you back at the start, try again.”

Well, you see, it's all about the magical power of the "off" and "on" buttons. When you turn something off, you're essentially giving it a chance to take a breather and clear its head, so to speak. And when you turn it back on, it's like giving it a fresh start, a clean slate. It's like sending it off to IT rehab for a quick reset.

Plus, let's face it, sometimes the machines just need a good kick in the circuits to get them going again. And what better way to do that than by turning them off and on again? It's like a gentle reminder that they're not the boss of us, we're the boss of them.

Of course, it's not a cure-all for every IT problem, but for those pesky glitches and hiccups that seem to crop up out of nowhere, it's a tried-and-true method that never fails. So go ahead, give it a try. Turn it off and on again. You might be surprised at just how effective it can be.

Moss

Think of a grid-like city, and you have to go to the supermarket starting from your house, you follow directions to get there but one time you make the wrong turn, and you get lost therefore you can't arrive to your destination.

When you turn off and on, is like you're transported back to your house and you can start again to follow instructions to arrive at your destination. It's almost the same with computers and devices.

Simply put, there are constantly numerous processes running in the background on your computer that you probably aren't aware of. All of them constantly use your computer's memory to some extent. They read and write stuff in your computer.

Now, there are two types of memory on your computer, volatile, and non-volatile. Volatile memory gets deleted when you reboot your computer whereas non-volatile stays in place.

Generally speaking, your computer has two types of memory, ROM, which is your long term storage (though the term ROM, which is short for read only memory, is kind of inaccurate, as it implies that you can only read what is stored, but not write to storage, or in other words, you can access the file, but not modify it), and RAM, or random access memory, which is your working memory.

Now, ROM is always non-volatile, but RAM isn't. RAM is, however, faster than ROM, which is why both types are used. Sometimes, what you need is the ability to read and write quickly rather than the ability to store a file long term.

What's any of this have to do with these processes running in the background? Well, as they run, they may store data in your RAM that just doesn't get deleted. Afterall, even the most avid PC users rarely let their PC run continuously for more than maybe 12 hours, so leaving some files undeleted in a place that gets reset anyway after a few hours isn't a big deal.

However, in the odd situation where this does break something, you can just reboot your PC and that solves it. Same thing with many other software programs. They store various types of settings in RAM. Often times, these are settings are things you're not even aware exist, because they run in the background, without your computer ever letting you know they exist in the first place. If something goes awry, restarting the computer will often fix it for the same reason.

Not just computers, but most complex machines tend to have some kind of "memory". Stuff like jukeboxes could work way before we had computers, they used circuits we call "electromechanical" to basically accomplish what computers do with bigger, bulkier components.

Let's stick with a physical example. Some motors are very precise about how far they'll move if they recieve power for specific amounts of time. So robot arms and other things that need to do repetitive motions follow a "program" that's really just them applying power to the motors in specific patterns. But if something goes wrong and a gear slips, that can muck everything up. That means the arm didn't move as much as it should have, so from that point on the program's just a little bit wrong. If it keeps happening, the robot arm won't be doing what it's supposed to and is likely going to cause damage to something.

The startup process for these kinds of machines involves getting it into a "known state". For this kind of motor, it means there's usually physical barriers that stop the motor from turning too far in one direction. So to get it in a "known state", when the machine starts up it will turn the motor in that direction until sensors tell it that it has reached as far as it can go. (Or, it turns for an amount of time guaranteed to put it in that position.) Now the system "knows" where the motor is again and is safe.

(More sophisticated motors have more sensors and can tell where they are, but they cost more and don't make this explanation work so well.)

That's kind of what can happen with computers and more sophisticated machines, too. Their program or even the circuits may have tiny problems that cause tiny mistakes. Those mistakes may not be harmful for the first few hours, which is why the developers didn't notice them. But over time those tiny mistakes might add up and start causing the program to do weird things, sort of like how if the gear for the robot arm slips the program is now incorrect because the arm is not in the position it should be.

The reason you have to sometimes leave it off "for about 5 minutes" is interesting. NORMALLY a good computer should go through all of its memory and set it back to a safe state when it starts up. But that can take a long time so it's a step that might get skipped. But most memory doesn't "hold" its value for very long if the power is not on, and eventually ends up in the known state anyway. So if the program doesn't clear memory at startup (or if there's a bug that causes it to miss some memory), turning off the power for long enough to make ALL of the memory reset can fix that little issue.

So it's kind of like if after you turn off the robot arm, you manually manipulate it into the "safe" position before turning it on. That makes sure it's in the state the program expects.

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Sometimes you need to not only shut down, but yank the power cable.

After shutdown, some components may still get power, I would guess to keep them warm and ready for reboot.

I've seen router problems which persist after shutdown / reboot, but fixed by unplugging the power for a minute before reboot.

It's a very simple process to understand. Most powered devices are designed to automatically configure or arrange themselves in a way that prepares them to perform whatever work they're intended to do. They're also often designed to return to a state when turned off that allows them to do the work needed at startup to prepare for use.

That work often requires a sequence of steps or has a number of parallel steps that are intended to occur in an order to achieve the device's purpose. Sometimes things can happen the push those steps out of order or into conflict, and trying to go back and sort out what exactly went wrong, correct it, and then correct all the subsequent steps that may have been impacts is impractical.

When you turn the device off, it returns to that pre-startup state, and turning it back on restarts all those steps it automatically does to prepare for use, and as long as whatever set of circumstances caused the original problem don't happen again, the device can return to normal operation.

Imagine a computer like a person. As you get tired you start to make mistakes. The more tired you are, the more mistakes you make and those mistakes stack up and lead to other mistakes. Little brain facts, clumsiness, not paying attention, etc. Sleep is a good reset of your mind and you wake up well rested.

Computers are similar. They start to have little mistakes as temp memory gets filled up over time. A power cycle resets that temp memory and clears any junk. Gives the computer a good night's sleep.

Well, it doesn't. Yes, it resets the state to the known good (see other comments), but it most likely doesn't fix the actual cause of the problem, but rather hides it.

Easiest way I have explaining it is it's like a zipper that went a little off track. Sometimes the only way to get that zipper right again is to undo the whole thing and start from scratch.

The little errors in software are like pubes getting stuck in your fly. Sometimes the zipper or software still kinda work, sometimes everything will be off by a bit, and sometimes it just fails completely and you have to start again.

When things run for a while they can have mess ups

Most startup processes on most items have a startup process which runs a very basic start of default services or actions.

By simply just turning the power on and off it allows the startup to run again and essentially reset and have no issues because it starts up correctly using the basic default startup parameters.

1. wipes the temporary memory (volatile). A program may have hit a loops (tried to follow instructions, but got lost and is now going in circles looking for a line of code that doesn't exist). If you shut it down, all those processes stop running, and the system starts each program over from scratch so the program knows "where" it is.

2. Most modern computers have a bunch of software dedicated to checking both software and hardware problems when it starts up. It can fix a lot of these.

3. Sometimes the issue is the user, not the system. Restarting it gets you back at the beginning of your task, and maybe you'll pay closer attention and get it right this time.

4. some updates don't apply until after a restart happens - these updates may fix your issue.

5. it kills all running program. You might have started something in the background that is taking up a ton of resources and causing the problem that you aren't even using. restarting will shut that down and let the programs you want to run have the resources it needs.

Software has logical ‘states’ that work best when they flow into each other as planned. If you have a bug and get into a weird state, powering down and up sends you back to the known initial state, from which things should progress as expected.

A lot of effort in embedded software goes into not getting into bad states and if you do, recovering, but sometimes mistakes are made, or management cheaps out and bugs remain.

Sometimes you have a bad day. Maybe you got a flat tire on the way to work or maybe you tore your favorite shirt. Then you find out that your crazy Uncle Bob is in jail again and that is going to mess with family plans, your friends cancel last minute on you, your randoms in your game of League are dogshit, etc etc.

Sometimes there's no saving a bad day. Sometimes, all you can do is go to sleep and start over fresh the next day.

When your computer first starts up, it initializes to a known good state. A lot of problems that happen in software are a result of things ending up in a bad state. By turning it off and on, you return to that original good state.

Take a game of chess for example, when you start, all the pieces are in known positions and you can start playing the game (good state). Now, say halfway through a game, someone bumps the table, and scatters all the pieces around (bad state). You don't know exactly where everything was, so the only fair thing to do is clear the board (turn off), and start a whole new game (turn on), thus returning the pieces to their starting positions (good state).

In addition to the other insightful comments, tech support often recommends turning it off and back on for a much simpler reason: the device in question could have been powered off in the first place. But if they ask it directly, “is it powered on?”, in all likelihood they are going to get a snarky “of course it is, who do you think I am”. Instead they ask for some placebo procedure like blowing on the power cable, and in a not insignificant portion of the cases the caller is going to realize who they actually are but will say “OK, that helped, thanks” without losing face.

I think the best way to answer this is to understand what is going wrong. What's causing the device to go wrong is that some sort of glitch--like a software bug, a hardware bug, an environmental glitch (power spike or drop), etc. has caused the system to be in a state that doesn't work. For example a software bug has overwritten the variable that tracks the number of players. or a hardware glitch where if the power drops for a millisecond or two, the DAC loses some sort of initial configuration.
So how do you fix that? Just turn the power off, then back on and the device will start back up in the initial, pristine configuration.

Because that's not real troubleshooting, instead it just lets you revert back from a known good state, the starting state.

Real software troubleshooting is not only expensive, but also out of regular user's capability to collaborate.

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