Lightbox is widely using in web page design. In short, Lightbox is simply an overlay image display on top of the current web page. When visitors click on a thumbnail picture on a webpage, the original size or enlarge image of the thumbnail picture will be displayed on top of the current page.
The main advantage of Lightbox is that visitors do not need to leave the current web page. This is illustrated in the diagram below:
There are many free jQuery Lightbox plugins on the Internet, choose one to suit your need.
In this example, I am using jQuery Lightbox 0.5 for the illustration.