Facing the Past and Future of HTML5
Discover the relationship between HTML5 and previous HTML versions such as XHTML and HTML 4.01. Learn about various doctypes, deprecated elements, and the use of frames and inline frames. Understand how to recognize old and new HTML markup and prepare for browser compatibility issues to better maintain and build web pages.
By now, you have learned about HTML5 and had to think of older HTML versions only tangentially.
In real life, you often meet old HTML dialects, including XHTML and other old HTML versions.
However, they are very close to HTML5 you learned in this book, but they may use HTML elements and attributes you do not know yet. On the other hand, HTML5 defines new elements that are not supported by all browsers, or not fully, but partially.
Old HTML dialects
At the very beginning of your first exercises, you met the <!DOCTYPE> tag that instructs the web browser about the version of HTML the page is written in. Since that, you have applied this tag many times in the form of ...