Markup: Elements, Attributes, and Values
(X)HTML is an ingenious system of including information about the content right in a text document. This information—called markup, accounting for the m in (X)HTML—can include formatting instructions as well as details about the relationships between parts of the document. However, because the markup itself is comprised chiefly of text, the document is practically universally accessible.
Elements are like little labels that identify and structure the different parts of a Web page: “This is a header, that thing over there ...