Ian "Hixie" Hickson is the author and maintainer of the Acid2 and Acid3 tests, the WHATWG HTML 5 specification, and the Pingback specification, and the early working draft of Web Applications 1.0. He is known as a proponent of Web standards, and has played a crucial role in the development of specifications such as CSS. Hickson was a co-editor of the CSS 2.1 specification and is one of the original co-creators of Flutter.