h1 {

color: blue;

text-align: center;

}

This will see every <h1> tag updated to display the text in the colour blue and centre aligned. Looking at this simple example should help you to begin to understand just how much time CSS can save you when building websites. Imagine if you had to change the style of each <h1> element manually?

id selector

Selecting an HTML element by id is very straightforward: you simply use the specified id prefixed with a ‘#’. As we highlighted in the HTML section, every id you use must be unique, and, therefore, must only ever apply to a single element. In this way, when we write a CSS rule for an id, that rule will only apply to that single element. Looking at the following example, we can see how this works in action: