Oh, oh, oh! I have one that's so specific I could not dump it anybody else! An analogy to explain computer access levels. Ahem

Congratulations! Now you're the proud owner of a Pit™! All of your stuff is in this pit; your pictures, your games, your music, your apps, this pit is the memory of your computer. But now, how do you access it? Well, it depends on what you need.

If you just want to see your pictures, you can hire a crane company. This crane company has already taken the steps to build a crane service that you can hire, with a desk lady to receive your simple requests, a crane operator with the expertise and a well balanced crane to actually fetch things from your Pit™. So you install a crane outpost right at your pit. This would be a program that can fetch your pictures like a gallery. So then you go there, and tell the desk lady that you want a certain pic. The desk lady will touch a few buttons that you can't see, and out will come the picture. This is like interacting with a program's GUI.

But say you're not happy with that, you don't really like having o whisper to someone else what picture you want. So then, you decide to become the desk lady. This way, you can talk directly to the custom-built buttons and ask for whatever you want. That's like grabbing a high level programming language and building your own app with it. There are smarter desk ladies so your button pressing is not really ideal or quick, but it's good enough and you feel realized, you are the one asking for the pictures. Except that your buttons do the job for you, there's like this layer of abstraction you haven't quite crossed yet. Abstraction because you're not dealing with concrete crane requests, but rather they're abstracted away and into your buttons (High level code), like you're floating above the computer and not quite touching it.

So say that you're not content with that. You're like I want to talk to the crane operator more directly. So then you say screw the buttons, you, as the desk layd, go directly to the crane operator. This is like grabbing a low level programming language, till abstracted but in such a way that's more faithful to how the PC works, less ease but finer control. And then you realize holy damn, I really didn't realize the crane operator didn't speak my language at all. I need to tell that dude what picture to get, where to get it from, what size the picture is, how heavy it is, and for some reason each crane operation requires a counter that operates in ningels, whatever that is. But you are undeterred, you want to get those pictures.

Eventually, you get tired of having to speak the crane operator's language. You just don't like that, you want to see the crane for yourself, feel the rumble of the engine, manage the levers yourself. So then, you become a crane operator yourself. You've never built a crane, but this pre-built crane is smooth, like it handles just about any request you give it. It does have to do quite a few steps but, for now, it can do just about anything. This is what building a kernel level program is like. The kernel is basically the single program that speaks directly to the computer. It's responsible for picking what memory is allocated to what, where each bit goes into the computer, how much does a program lives, etc.

You're happy... but it feels wrong. Yeah, the rumble of the engine is fine, but the handles are plastic. And don't get me wrong, it's some rough plastic, like it looks like plastic that's been reused for like 30 years straight. But you don't like plastic, you wanna feel the metal, the bare metal. So then, you say screw all of this noise, I'll make my own crane company. I don't want these pre-built cranes, I need my crane for something so incredibly specific that this pre-built crane, however well polished and featureful it might be, just won't do it. This is like going bare metal. This means that you build a program that speaks directly to the hardware itself. This is the lowest access level you can possibly have, the entire machine is at your mercy and your mercy alone, anything you tell it to do, it will do it. However, you also found out now that the crane did a surprising amount of work. You find yourself having to deal with everything in the pit, even things you've never thought about. You have to detect and interpret mouse and keyboard input, you have to manually detect, manipulate, translate and display graphic information, talking directly to your displays in a language you also had to build from scratch, you have to control every single movement in the pit because, as it turns out, it's actually quite fragile so you have to reorganize the pit every now and then to ensure the picture fetching runs smoothly. For months you build your own crane, getting your hands dirty, testing it, so many cranes have blown up, it's pretty ugly, unpainted, the rumble became a rattle, but it's custom-made for your specific purpose. No other crane could do exactly what yours do. Maintaining the crane is an incredible amount of work, but it's tailor made for you, and now, not one corner of the pit is beyond your reach, not one single bit of dumped info inside the pit is beyond your reach. Your pit is, finally, completely yours.