Answer 1

https://developer.mozilla.org/en-US/docs/Learn/Getting_started_with_the_web/HTML_basics

HTML Element consists of three parts : Opening tag, content and closing tag.

https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes

Attributes of HTML elements are additional values that configure the elements or adjust their behavior in various ways to meet the criteria the users want.

Read the tutorial on MDN Doc:

https://developer.mozilla.org/en-US/docs/Web/HTML