You've got the main ideas—now it's time to dive into the nitty-gritty.
You've noticed that when we've asked you to set color properties using CSS, we've been having you type things like
color:red. You may have asked yourself: what if I want maroon? Or fire engine red? Or more of a red-orange? Does CSS know all those words?
The answer is no. It can, however, understand millions of colors in the form of hexadecimal values.
You're already extremely familiar with decimal values: it's everyday counting! You know when you see a number (e.g. 1,432) that each digit can only be the ten values 0 through 9. Because there are only ten possibilities, we say that regular counting is base-10.
Hexadecimal counting is base-16. Each digit can be the numbers 0 through 9 or the letters a through f! Crazy, right? Check it out: