One of the most popular design patterns in Web Automation is the so-called Page Object Pattern. The famous programmer Martin Fowler was one of the first that mentioned Page Object as a pattern and explained its usage. You may not be able to find it in the list of all "official" design patterns because the community started using it recently. Most of the other design patterns have been about for more than 20 years. You can find more about the usage of design patterns in the automated testing in my series- Design Patterns in Automated Testing Series.

In general, a page object abstracts an HTML page. It provides an easy to use interface for manipulating the page elements without searching for them in the HTML.