GitHub is introducing Identicons, colorful 5×5 pixel sprites generated for users without a Gravatar, by using a hash of the user's ID to create unique patterns and colors. This system ensures a vast array of unique Identicons by turning pixels on or off based on the even or odd values within the hash. Users who currently use a Gravatar but are curious about what their Identicon would look like can generate it by using a specific URL and substituting their GitHub login. The announcement is made by Jason Long, offering a creative visual identity for users on the platform.