For web design purposes, a div width is simply the width of a section of content, usually measured in pixels. The div element is used as a layout tool to separate content into sections for styling purposes. These sections of content can than be targeted and customized using CSS.
Although a number of different measurement types can be used to define the width of a div, pixels is the most common measurement for web design. Web developers may convert these pixel measurements to percentages when working on dynamic web pages, where the div elements scale in size to match the user's screen.