Final answer:
In CSS, you can use the class and id selectors to customize HTML element styles.
Step-by-step explanation:
In CSS, you can use the class and id selectors to customize your own HTML element styles. The class selector is denoted by a period and can be applied to multiple elements, while the id selector is denoted by a pound sign and is unique to a specific element. By assigning a class or id to an HTML element and then defining CSS rules for that class or id, you can customize the styling of that element.