CSS stands for Cascading Style Sheet.

Lets worry about the second part of that phrase first. A Style Sheet is just some text that styles something.

CSS styles web pages. That means it will describe things like the colour of the background, the width of the space allowed for the writing, and even things like the style of the writing. These are CSS rules.

Without CSS most websites should still work but they would look very boring.

The “Cascading” part of CSS just means that the properties that CSS describe can fall down to lower levels.

This means that you can say “make all text in this area blue”, and then you can specify a rule further down the cascade that says “make this bit of text red”, all the text would be blue except for the specific thing we asked to be red.

Example

An example of the CSS we talked about could be;

body {
 color: blue;
}

.warning {
  color: red;
}

This will turn all text within your main body (all of the page) blue, but if we have an element with the class of warning then the colour will be red.