If you generate images dynamically using GD library you can't simply output them to the browser like HTML content. Instead you have to: (1) Store dynamically generated image somewhere on your server; (2) Output img tag to the browser; (3) Remove the image after it was sent to the browser. This script makes all these steps for you. The images are stored in MySQL database. After an image is fetched to the browser it is removed automatically. If the image was not requested by the browser (the user lost connection, etc) it is still removed after a certain time.