Acid1, originally called the Box Acid Test, is a test page for web browsers. It was developed in October 1998 and was important in establishing baseline interoperability between early web browsers, especially for the Cascading Style Sheets 1.0 specification. As with acid tests for gold which produce a quick and obvious assessment of the quality of a piece of metal, the web acid tests were designed to produce a clear indication of a browser's compliance to web standards.