A HyperText Markup Language (HTML) countdown is an object, script or piece of code that deducts time from a counter or displays the remaining period of time until a certain date. Although it is not necessary, an HTML countdown is usually displayed visually for the user to see. It is possible to attach a specific action to be taken, such as loading another web page or switching to a different countdown date, when an HTML countdown reaches the target number, or zero. Most often, the digits used to display the time remaining in a countdown can be customized to fit with a certain design theme or to emulate real countdown clocks. Depending on the language and method used to implement an HTML countdown, some browsers might not display the numbers because of user preferences or security settings.
One use for an HTML countdown is to force a user to pause and view an advertisement before being allowed to enter a particular website. This timer works in conjunction with HTML cookies to determine whether a user has waited through the countdown before access to the site is permitted. If a user attempts to bypass the countdown by entering a site’s address directly into a browser, the main site can check a cookie on the user’s system to see whether the timer page was viewed until the countdown expired.
In most cases, an HTML countdown uses a set of images to display the numbers and any other information necessary. These images include the container for the numbers, which can be made to look like almost anything, and the numbers themselves. The images for the numbers can usually be customized so they emulate a digital readout, hand-written characters or even abstract symbols. When used in conjunction with cascading style sheets (CSS), the positioning of the countdown object can be very precise and fluid.
More complex HTML countdown programs can actually define an entire image that emulates real-world analog devices. One example is a standard analog wall clock with minute and hour hands that move as the time decreases. Artistic renderings, such as obfuscated clockworks, also can be used to represent the movement of a countdown.