• This guide provides study notes for web technology courses, specifically covering HTML.

HyperText Markup Language (HTML)

• HTML developed by Tim Berners-Lee at CERN in 1989, gaining popularity with the Mosaic browser in 1993, developed by Marc Andreessen at NCSA.
• HTML is comprised of elements recognizable by graphical and textual browsers, displayed in a specific way for the user.
• Graphical and textual browsers, also known as Web browsers, access Web pages stored on Web servers via HTTP protocol.
• HTML pages marked with HTML tags, displayed in a specific way by web browsers.

HTML Development and Versions

• HTML evolved from a text-based system with links to other pages, initially aimed at connecting scientific papers.
• HTML involves marking text to link to other documents, using tags to indicate how elements should be displayed.
• An HTML page consists of text content and HTML tags, enabling the inclusion of other Web documents.
• 1989 is considered the formal year of HTML's creation.
• HTML+ appeared in 1993
• HTML 2.0 was released in November 1995 under the IETF, while HTML 3.0 was released in 1996.
• In January of 1997, the World Wide Web Consortium (W3C) developed HTML 3.2.
• HTML 4.0 was released in December 1997, and HTML 4.01 in December 1999.
• XHTML 1.0 appeared in January 2000, and XHTML 1.1 in July 2007.
• HTML5 has been in development since 2007; HTML 5.0 was recommended in 2014, and HTML 5.1 in 2016 by W3C.
• WHATWG and W3C agreed to collaborate on a single HTML version in 2019.

Additions and Changes in HTML5

• HTML5 brought additions, obsolete tags, and new attributes.
• A key difference between HTML and XHTML is that XHTML is stricter regarding correctness.

Simple HTML Example

• A simple Web page displays an image, a main heading, and a numbered list of instructors.
• HTML tags are used to mark up the text, directing the Web browser to display it in a specific format.

Definition of HTML

• Hypertext Markup Language (HTML) defines structure, presentation, and semantic information and is used to create platform independant documents.
• HTML documents consist of hypermedia, including text, images, audio, and video.
• HTML documents, as SGML documents, designed for broad information representation.
• HTML relies on Document Type Definition (DTD) to define tag syntax, conforming to ISO Standard 8879:1986.
• HTML tags can represent news, emails, documentation, multimedia, menus, database queries, and structured documents.

Roles in HTML Usage

• HTML can be used by creators of static pages who compile content with HTML tags.
• Web app creators, who use databases and programming languages to present dynamic content.
• HTML is a user's tool for accessing content is presented.
• Web applications now enable users to contribute content.
• Creating HTML pages or web applications requires autorski tools for HTML and web documents, a web browser, and a web server.

HTML Compliance and Validation

• Web designers need to ensure HTML compliance with their chosen version.
• Resources like http://caniuse.com/ offer assistance with HTML version support across browsers.

What is an HTML Page?

• An HTML page is a text-based document with a .html or .htm extension.
• A multimedia/hypermedia document in text/html format, according to Multipurpose Internet Mail Extensions (MIME).

Web Browsers

• Web browsers are applications for viewing HTML pages with categories like text-based and graphical browsers.
• Graphical browsers now dominate, but text-based browsers like Lynx still exist, with the first being available at https://worldwideweb.cern.ch/.
• Popular graphical browsers are Chrome, Firefox, Safari, Opera, and Edge
• Additional browser functionalities influence user experience, privacy, and security, making same pages in all browsers and minimal display differences.

HTML Page Content

• HTML page content includes visible elements (titles, text) and invisible elements (meta instructions, design code).
• A Web page’s content is either embedded directly or referenced externally, images, design instructions.
• Special tags allow browsers to embed external documents or provide links, depending on the document type.

HTML Language Elements

• HTML uses tags (elements) to format content, each having a unique name using alphanumeric ASCII characters without special characters.
• HTML elements consist of a tag name enclosed in angle brackets and include content and matching opening and closing tags, the closing tag denoted with a forward slash.

Types of HTML elements:

• Empty: Contain to no content, therefore no closing tag.
• Raw text: Includes text with restrictions.
• Replaceable Character Data: Contains text and character references.
• Foreign: It treatesed as self-closing with text but without specific characters.
• Normal: All other elements.

HTML Element Attributes

• HTML tag may have one or more attributes to define a name and value separated by an equals sign.
• A blank attribute value doesn't require an equals sign or quotation marks, while values with spaces need quotes.

Variations of HTML Elements:

• Element : The element without attributes.
• Element attribute: The element with an attribute but with no assigned value.
• Element attribute="value" is and element with an attribute that has a value assigned to it. This value doesn't need any additional quotation marks.
• Element attribute="value" is and element with an attribute that has a value assigned to it. In this case the value is surronded by quotation marks and it's mostly used when there are multiple words.
• Element attribute1="value1" attribute2="value2" is and element with multiple atrributes which all have values assigned to them.

Common HTML Attributes

• Ids used for CSS/Javascript/internal links.
• Title and lang elements are language specifications.
• Class and style manage CSS styling data attributes custom.
• Event handlers are onfocus, onblur, onsubmit, and onmouseover.

Character Display

• Text documents use encoding like UTF-8.
• Text editors reveal document encoding but display character symbols as strange.
• HTML5 uses UTF-8, replacing the older ISO 8859-1 standard, using logical names, decimal, or hexadecimal numbers to represent symbols.

Structure of an HTML Document

• An HTML document starts with a preamble indicating HTML version. For HTML5, it is "".
• Followed by the root element with optional lang and dir attributes for language and text direction.
• Inside , defines the document’s head section, and defines the body section consisting of visible and invisible components.

[Differences Between HTML and XHTML]

• XHTML, stricter than HTML, needs closing tags and requires tags' order.
• XHTML treats big and small letters differently and requests the values of the attributes to be surronded by quotation marks.

Key Differences according to [W3Schools, 2021]:

• and xmlns are mandatory.
• Ugnježdivanje oznaka must be followed.
• Tags must be closed for all types of elements.
• Tags or names must be in lowercase.
• All elements' attributes must have quotation marks.

Head Section

• HTML document's head contains metadata, which search engines use.

The head section contains: