I have often wondered why strict parsing was not chosen when creating HTML. For most of the Internet history, browsers have accepted any kind of markup and tried their best to parse it. The process degrades performance, permits people to write gibberish, and makes it difficult discontinue obsolete features.
Is there a specific reason why HTML is not strictly parsed?
Best Answer
The reason is simple: At the time of the first graphical browsers, NCSA Mosiac and later Netscape Navigator, almost all HTML was written by hand. The browser authors (Netscape was built by ex-Mosaic folks) recognized quickly that refusing to render incorrect HTML would be held against them by the users, and voila!