When building an MVC application, layouts are used to share common elements like headers, navigation bars, and footers across all pages. Instead of repeating this structure in every view, a single layout wraps around each page's content. This saves time and makes maintenance easier, since updating the layout in one file updates it across the entire application.

It is also important to understand the difference between layouts and templates.

A layout defines the overall page structure, while templates (views) provide the unique content for each page.

In this layout file, you see a basic HTML structure with a header, navigation, a main content area, and a footer. The key part is the '$content' variable, which acts as a placeholder for the unique content of each view. When rendering a page, the controller will load the specific view, capture its output, and inject it into this layout at the '$content' location.

Here, both home.php and about.php are simple view files containing unique page content. The render.php script demonstrates how you can use output buffering to capture the output of a view, assign it to '$content', and then include the layout. This means both views are wrapped in the same layout, sharing the header and footer, but displaying different content in the main section. By using this technique, you avoid repeating HTML structure and keep your code DRY (Don't Repeat Yourself).