I see this term “full stack developer” pop up all the time, does anyone want to explain what it means? A dev who knows all parts of the stack, and a stack is what..?

As far as i know it's someone who can do both backend and front end (web)!

I'm a "full stack data analyst" which means that I can write ETL into a database, build the database schema, write the API out of the database, write the formula, and build the reporting front end.
The same thing would be for applications or web sites; but using their technology or stack.

IMHO, someone who actually knows enough to function as a team's database expert, business logic guru, UX guy, or system architect. It's a term that's gotten tossed around so damn much that it's being worn by anyone who can make a table, create a POCO, vertical align text on a button, and build a wireframe mockup in Pencil. It's just another useless tech buzz word these days.

In my experience full stack means you can:
- Design UI (UX)
- Develop UI
- Develop backend
- Architect, integrate and interface with databases

Take that with a grain of salt though, because just like AGILE, full stack has become more of a buzzword than anything.

It's when companies are too cheap to hire proper backend devs and they let the front end guy do something in node js because he knows js.

Full stack software engineer means you are proficient in every layer of the stack: from UX & UI design to implementing a front end, to implementing the back-end including a correctly designed database. I don't mean basic knowledge in all these areas: you should be expert enough to create the whole application by yourself. Adding some devops experience makes the stack even fuller.

@Lightor I agree with you that it is becoming a buzzword however there are indeed software engineers who truly master the full stack. For me, personally, I love both front end and back end and as such have always worked on both. As I have a degree in software engineering I do consider myself full stack, even more when I encounter other (dedicated) front end developers who can't create a decent lay out, don't understand some js code, etc. Same for some dedicated back-end dev that doesn't know shit about for example sql.