Ask HN: What is “full stack” actually?

I define it in practical terms: can you start from scratch and deliver and maintain a product? This is a term that's often used to describe web or mobile development, so in this context I take it as being able to do things like platform setup and maintenance, write a backend, write a front-end, do the design, etc.

This term really caught on with people who develop for the web because there actually is a divide here: some people really prefer the front-end work (JS/HTML/CSS), some people prefer the backend work (sysadmin/app logic/data stores) and some people prefer both.

So basically, if someone says "full stack", they likely mean that you can develop and run the entire product, not just a part of it.

Having said that, I strongly encourage everyone to go deeper. Learn some C. Figure out the difference between a function and a syscall. Understand what the kernel does and how it works (whichever kernel you happen to use). Write a toy libc. Program for a microcontroller (try adding RAM to a microcontroller circuit for added fun). Play some Minecraft. Write a bit of assembly. Create a data store. Develop a JS framework for DOM manipulation. Create a toy programming language. Write a malloc implementation. Write a kernel module (maybe a driver to that microcontroller device you put together). Write a web server. I find that the more of this kind of stuff you do, the more aware you become of what `display: block;` will do and how to structure your code better.

I like the "he can make an application on his own" definition, but this masks the juicy part of this question, which is "well, what does that take?" Realize that, these days, you could build an arbitrarily complex program using nothing more than GitHub Pages with a dynamic shared data structure layered on and connected with some javascript, e.g. with Firebase. Personally, I'd consider that to be a kind of a stack.

But yeah, most people don't design software like that yet, so they mean server rendered pages, which means a server container of some sort, an application "middleware" process (something like node or PHP or Java), and a database process, all of which allow the user to, from one perspective, "pan and zoom" across some data corpus, and gives them the right to poke that data corpus at a few points.

"Full-stack" actually sounds to me like a stack overflow waiting to happen :)

Full stack software engineer, to me, means knowing the full stack of abstractions from Javascript / Python / Ruby through C to CPU machine code for at least one architecture. Knowing hardware design isn't particularly relevant to software outside knowledge of how cache associativity works, cache hierarchy, CPU interrupts, page faults, that kind of thing - the API at the CPU architecture level. If you're writing device drivers, you've gone beyond full stack software - you've got to know more about specific hardware.

Full stack in practice means knowing where to look on the next layer down when something goes wrong, and having good intuitions about how things behave and how you can expect things to be implemented given what's available.

Full stack web engineer is less about depth of abstractions and more about breadth; knowing the browser, a back end language, a database, and enough about system administration to put it all together.

Full stack means you're average at frontend and backend.