HTML5 is the new standard for HTML that includes new semantic elements, forms, media playback, and graphics capabilities. It is being developed cooperatively by the W3C and WHATWG to address changes on the web since the previous HTML 4.01 standard from 1999. Key new features include the canvas element for 2D drawing, video and audio elements, improved form controls like date pickers, and local storage capabilities. While still a work in progress, many modern browsers already support important HTML5 features through various specifications.