Java
Used in many applications that need to be multi platform. Uses more memory than some other languages due to the fact it uses its own environment to run programs.
CSS
Also known as Cascading Style Sheets. What makes html look pretty.
JavaScript
A powerful tool for client side html manipulation. Almost every website uses it, and can be used for analytics, games, or functionality.
HTML
The skeleton of a webpage. Every site uses it, regardless of the server back end. Has a stricter variant called XHTML.
C#
A multi platform language that is compiled. Used with ASP.NET and Unity.
PHP
An open source server side programming language. Useful for getting data from a database and displaying it on a web page.
SCSS
A language that compiles into CSS. Allows for nesting, variables, and mixins.
Razor
A simple programming syntax used to display output of C# or Visual Basic. Used in templates for ASP.NET MVC.