Lightbox plugins are tools used on websites to display images, videos, or other content in an overlay on top of the current page. When a user clicks on a thumbnail or link, the lightbox effect dims the background and highlights the selected content, creating a focused viewing experience. This feature is popular for galleries and portfolios, as it allows for easy navigation without leaving the main page. These plugins are often customizable, allowing developers to adjust styles, animations, and behaviors to fit the website's design. Many lightbox plugins support various media types, including images from Flickr or Instagram, making them versatile for different content needs.