1. A method to select images for a markup language document, the method comprising: encoding an instruction in the markup language document, the instruction to be executed by one or more processors to select an image for insertion into the markup language document; generating a pre-determined number N of random numbers; selecting a pre-determined umber of N images from a group of images using the N random numbers to select the N images from the group of images, the pre-determined number of N images being specified in the instruction; placing the pre-determined number of images in the markup language document at one or more locations defined in the instruction, the pre-determined number of N images to be displayed on one or more web pages, and selecting the group of images for a pool of images from a gallery containing images available for display, the selecting of the group of images being performed using an administration tool, the selecting the group of images for the pool of images includes: obtaining filtering criteria; identifying an image from the gallery based on the filtering criteria; and adding the identified image to the pool of images.