Unsupported tags

Question

Some of the tags such as <marquee> and <font> are not supported in HTML5. How is it that the web browser can still interpret the code and execute it perfectly even though some of the elements in the code are not supported by the language being used?

Answer 1

Browser vendors keep the support for code backward compatibility reasons I suppose, until later, when everyone has fully adopted the new standard, or if they came up with something to take the place of the obsolete tags with same functionality.

Answer 2

I noticed it too when I used marquee in a code of mine (which Nikolay pointed out). Thanks for explaining Ipang!