- HTML / XHTML - markup language for creating web pages (there's also CSS).
Most learning resources mix those technologies. It's ok if the goal is to quickly add some interaction to web page, but it makes it harder to learn more complex stuff.
There's also short (about an hour) introductory course.
What to do next?
After you learn basics - it may be interesting to examine sources and play with JS toys
or some of top JS Projects on GitHub.
By Alex Craft