New features of HTML5
1. Semantic tags: <hrader></header><nav></nav>etc.
2. Painting canvas
3. SVG drawing
4. Video and audio, video and audio elements for media
5. Input enhanced form controls: calendar, date, time, email, url , search
6. Local offline storage localStorage long-term storage data, the data is not lost after the browser is closed;
sessionStorage data is automatically deleted after the browser is closed
7. New technology webworker, websocktGeolocation
removed elements
Pure performance elements: basefont, big , center, font, s, strike, tt, u;
elements that negatively affect usability: frame, frameset, noframes;
