How do you select an element with an ID in CSS?

To select an element with a specific ID in CSS, you use the hash symbol (#) followed by the ID name of the element. This syntax allows the CSS rule to target the unique element identified by that particular ID, as IDs are intended to be unique within a page.

Using # before the ID name clearly indicates to the browser that you are referencing an ID selector. This is part of the CSS selector syntax that defines how certain elements are matched and styled. The ID selector is effective for applying styles specifically to the single element that has that ID, ensuring that the styles do not inadvertently apply to multiple elements.

The other methods mentioned do not conform to the correct syntax for selecting an ID in CSS, which clarifies why they would not be effective. For example, using a dot (.) denotes a class selector, while the asterisk (*) represents the universal selector, which selects all elements. Simply writing the ID name without any symbol would not work as it does not utilize the required selector syntax.