HTML is a markup language that defines the structure of your content. HTML consists of a series of elements, which you use to enclose, or wrap, different parts of the content to make it appear a certain way, or act a certain way. The enclosing tags can make a word or image hyperlink to somewhere else, can italicize words, can make the font bigger or smaller, and so on.

"Hypertext" refers to links that connect web pages to one another, either within a single website or between websites. Links are a fundamental aspect of the Web.

Applications

• Web development
• Internet navigation
• Responsive Design

HTML (HyperText Markup Language) is the most basic building block of the Web. It defines the meaning and structure of web content. Other technologies besides HTML are generally used to describe a web page's appearance / presentation (CSS) or functionality / behavior (JavaScript).

Anatomy

Opening tag: This consists of the name of the element, wrapped in opening and closing angle brackets.

The closing tag: This is the same as the opening tag, except that it includes a forward slash before the element name.

The content: This is the content of the element, which in this case, is just text.

The element: The opening tag, the closing tag, and the content together comprise the element.

Anatomy of and HTML document

Doctype. It is a required preamble. In the mists of time, when HTML was young (around 1991/92), doctypes were meant to act as links to a set of rules that the HTML page had to follow to be considered good HTML, which could mean automatic error checking and other useful things.

This element wraps all the content on the entire page and is sometimes known as the root element.

This element acts as a container for all the stuff you want to include on the HTML page that isn't the content you are showing to your page's viewers.

This element sets the character set your document should use to UTF-8 which includes most characters from the vast majority of written languages.

This sets the title of your page, which is the title that appears in the browser tab the page is loaded in.

This contains all the content that you want to show to web users when they visit your page, whether that's text, images, videos, games, playable audio tracks, or whatever else.

Element Content

The content of an HTML element is the information between the opening and closing tags of an element.

1. List Item: li
2. Ordered List: ol
3. Unordered List: ul
4. Video: video
5. Emphasis: em
6. Division: div
7. Line Break: br
8. Headings: h1-h6
9. Paragraph: p
10. Span: span
11. Strong: strong

CSS selectors define the pattern to select elements to which a set of CSS rules are then applied. CSS selectors can be grouped into the following categories based on the type of elements they can select.

Universal Selector

Selects all elements. Optionally, it may be restricted to a specific namespace or to all namespaces.

Selects all elements that have the given node name.

Selects all elements that have the given class attribute.

Selects an element based on the value of its id attribute. There should be only one element with a given ID in a document.

Selects all elements that have the given attribute.

The: pseudo allow the selection of elements based on state information that is not contained in the document tree. Example: a:visited will match all < a > elements that have been visited by the user.

Selects all elements that have the given attribute.

All the documentation in this page is taken from MDN