Anyone doing frontend web development will have at least three: html, css, and javascript.<p>More experienced developers will add a preprocessor for each of those: slim (or haml, jade, erb, etc.), scss (or less, sass, etc.), and coffeescript. You're writing in the preprocessor, but debugging in the language it compiles to, so we're at at least six.<p>Now if you're programming a webapp with an actual backend, you'll need to use some middleware:either Ruby on Rails (my personal favorite), Python's django, Cake PHP (or whatever the cool kids on PHP are using these days), C#'s .NET, or Perl's dancer. The reason Node.js was a big deal was that it let you save a language here: you could re-use your javascript skills on the backend. The framework is so dramatically different, though, that I'd still count it as another language.<p>Now we're at seven.<p>Presumably you'll be interacting with some kind of API that uses either JSON or XML, so we'll call it eight.<p>Maybe your ORM (object-relational mapper) isn't quite robust enough to handle a query you need to make to your database, so you have to dip a bit into SQL (or Mongo, Redis, or whatever popular database you happen to be liking right now). You could potentially skirt this by using a service like Firebase that will let you keep your javascript and json skills for your database, but I'm still counting this as nine.<p>If you're just an app developer, and you either work on some kind of team that has other people that like to do this next part, or you're rich and can afford heroku, then you can stop here. Otherwise we've got a few more.<p>To deploy your app you've got to know how to log into your server and install your app dependencies, so you've got to learn bash (and a lot of other <i>nix tools, like ssh, scp, tmux, and vim, but those aren't really </i>languages<i>). Ten, easy.<p>One of the things you have to install is a web server like Apache or nginx. The config files of these things are a language unto themselves: they're both </i>kind of* XML-ey, but not really. I'm counting this as eleven even though it's usually something people just pick up by changing variables of, and nobody's actually writing in the stuff.<p>So a minimum of eleven. Personally, I also take notes in Markdown, jump between projects that are using different preprocessors and backends, and get myself into more trouble than I should on the server side. On a given day I think it's fair to say this could hit twenty.<p>And that, ladies and gentlemen, is how I almost always won the "who knows the most programming languages" dick-swinging contests in high school and college.