What is HTML and CSS?

What is HTML?
Rundown:
The easy answer is that html is the language of web pages.

In Depth:
HTML (Hypertext Markup Language) is a programming language used on the WWW (World Wide Web) also know as the internet in order to create web pages. Web browsers like internet explorer and firefox then read the HTML and display it so that you are able to view it. HTML is actually a very simple language once the basic concepts are understood. Just remember HTML is a client-side language which means the data is interpreted locally on your computer, not from the server. If you don't understand this, really its ok. You don't need to know it to have a profile.
W3Schools HTML Tutorial, HTML Goodies



What is CSS?
Rundown:
They define how to display HTML elements.

In Depth:
CSS (Cascading Style Sheets) define how to display HTML elements. They are normally stored in Style Sheets (.css), they were added to HTML 4.0 to solve a problem. CSS is a huge breakthrough in Web design because it makes it possible for developers to control the style and layout of multiple Web pages all at the same time! This might be seem quite irrelevant to you know, but once you're hooked on myspace you'll know all about it.
W3Schools CSS Tutorial