[johan_larson]

My working definition of "full-stack developer" boils down to "can write a complete web application". That requires substantial skills in the browser (HTML/CSS/JS/jQuery), server (Python/Django, perhaps), and storage layer (MySQL is a common choice).

This definition omits some things that become more important as the application becomes larger, such as cloud deployment, performance optimization, project management, and designing for reliability. But I think of those as more architect or project manager skills, rather than developer skills.

I should add that all three tiers are complicated enough to have specialists of their own. It's perfectly reasonable to be a database expert, full stop. But there seem to be a lot more opportunities for people who know the whole stack.