"Because I can make good $," "I don't like to dress up or shave," and "because I loved the movie Hackers," are not good enough answers. Well… a comment about Hackers might fly but make sure you have a real backstory that describes your "Aha!" moment.
HTML elements communicate to the browser how to render text. When surrounded by angular brackets <> they form HTML tags. For the most part, tags come in pairs and surround text.
The term DOCTYPE tells the browser which type of HTML is used on a webpage. In turn, the browsers use DOCTYPE to determine how to render a page. Failing to use DOCTYPE or using a wrong DOCTYPE may load your page in Quirks Mode.
Yes jQuery cab be used to make an AJAX request.
include() will raise a warning if it fails, require() will raise a fatal error.
Quirks Mode is a default compatibility mode and may be different from browser to browser, which may result to a lack of consistency in appearance from browser to browser.