.HTML File Extension

Hypertext Markup Language File

Developer WHATWG
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What is an HTML file?

An HTML file contains Hypertext Markup Language (HTML) that formats the structure of a webpage. It is stored in a standard text format and contains tags that define the page layout and content of the webpage, including the text, tables, images, and hyperlinks displayed on the webpage. HTML files are widely used online and displayed in web browsers.

More Information

Screenshot of a .html file in Adobe Dreamweaver 2021
HTML file open in Adobe Dreamweaver 2021

HTML was introduced in 1991 by Tim Berners-Lee and other CERN engineers as a way for web browsers to interpret and display webpages. Since its release, it has become a standard in web development and has gone through multiple revisions, which include HTML 2 (1995), HTML 3 (January 1997), HTML 4 (December 1997), and HTML 5 (2014).

The Web Hypertext Application Technology Working Group (WHATWG) develops and advances HTML. The group was founded in 2004 and consists of major browser developers, including Google, Microsoft, Apple, and Mozilla.

The markup language features HTML elements that make up the structure of webpages. Typically, each element includes an opening tag enclosed in angle brackets (<tag>) and a closing tag enclosed in angle brackets but with a forward slash preceding the tag (</tag>).

Some examples of basic elements include:

  • <head> - Head tag used to contain metadata about a webpage
  • <body> - Body tag that defines the body of a webpage
  • <h1> - Text header tag used to create a text title in a webpage
  • <p> - Paragraph tag used to define a paragraph in a webpage
  • <img> - Image tag used to embed an image in a webpage
  • <ul> - Unordered list to create a bulleted list in a webpage
  • <div> - Divider tag used to create a section in a webpage

Over time, other web technologies, such as Cascading Style Sheets (CSS) and JavaScript, have been introduced to enhance webpages. You will most likely find CSS or JavaScript code or references to .CSS or .JS files in modern HTML webpages.

Web developers often create and edit HTML files, then upload them to web servers that web browsers parse when a user visits webpages. If you are an average Internet user, you most likely will not see the HTML source code since your web browser parses it in the background.

However, you can still view the HTML of a webpage with a web browser by following these steps specific to the browser:

  • Google Chrome (Windows) - Select More tools → Developer tools
  • Google Chrome (Mac) - Select View → Developer → View Source
  • Mozilla Firefox - Select Web Developer → Page Source
  • Microsoft Edge - Select More tools → Developer tools
  • Apple Safari - Select Develop → Show Page Source

NOTE: Most pages within static websites have an .html extension, while pages within dynamic websites may have a .php or .asp extension.

Common HTML Filenames

index.html - The main, or index, HTML file that's loaded when a client web browser requests a web server directory. For example, when http://www.sampledomain.com/ is requested, the web server loads http://www.sampledomain.com/index.html by default, unless it is configured to use a different file.

default.html - The index file often used by Windows web servers such as Microsoft IIS.

How to open an HTML file

You can open and edit HTML files with various source code editors and web development applications. Microsoft Visual Studio Code (multiplatform) is a helpful source code editor and Adobe Dreamweaver (multiplatform) is a popular web development application.

Since HTML language is saved in plain text, you can also open and edit HTML files with a basic text editor, such as Microsoft Notepad (Windows) or Apple TextEdit (Mac). However, these text editors do not come with features included with source code editors and web development apps that make it easier for developers to code.

You can preview an HTML webpage by opening it with a web browser, such as Google Chrome (multiplatform), Microsoft Edge (multiplatform), Mozilla Firefox (multiplatform), or Apple Safari (Mac and iOS).

Programs that open HTML files

Verified by FileInfo.com

The FileInfo.com team has independently researched the Hypertext Markup Language file format and Mac, Windows, Linux, Android, and iOS apps listed on this page. Our goal is 100% accuracy and we only publish information about file types that we have verified.

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