An HTML editor is a program used for editing HTML, the markup of a web page. Although the HTML markup in a web page can be controlled with any text editor, specialized HTML editors can offer convenience, added functionality, and organisation. For example, many HTML editors handle not only HTML, but also related technologies such as CSS, XML and JavaScript, or ECMAScript. In some cases, they also manage communication with remote web servers via FTP and WebDAV, and version control systems such as Subversion or Git. Many word processing, graphic design, and page layout programs that are not dedicated to web design, such as Microsoft Word or QuarkXPress, also have the ability to edit & export HTML documents.

Text editors intended for use with HTML usually provide at least syntax highlighting. Some editors additionally feature templates, toolbars, and keyboard shortcuts to quickly insert common HTML elements and structures. Wizards, tooltip prompts, and autocompletion may help with common tasks.

Text editors commonly used for HTML typically include either built-in functions or integration with external tools for such tasks as version control, link-checking and validation, code cleanup and formatting, spell-checking, uploading by FTP or WebDAV, and structuring as a project. Some functions, such as link checking or validation, may use online tools, requiring a network connection.

Text editors require user understanding of HTML and any other web technologies the designer wishes to use, like CSS, JavaScript and server-side scripting languages.

To ease this requirement, some editors allow editing of the markup in more visually organized modes than simple color highlighting, but in modes not considered WYSIWYG. These editors typically include the option of using palette windows or dialog boxes to edit the text-based parameters of selected objects. These palettes allow editing parameters in individual fields, or inserting new tags by filling out an onscreen form, and may include additional widgets to present and select options when editing parameters (such as previewing an image or text styles) or an outline editor to expand and collapse HTML objects and properties.

WYSIWYG HTML editors provide an editing interface that resembles how the page will be displayed in a web browser. Because using a WYSIWYG editor may not require any HTML knowledge, they are often easier for an inexperienced computer user to get started with.

The WYSIWYG view is achieved by embedding a layout engine. This may be custom-written or based on one used in a web browser. The goal is that, at all times during editing, the rendered result should represent what will be seen later in a typical web browser.

WYSIWYM (what you see is what you mean) is an alternative paradigm to WYSIWYG editors. Instead of focusing on the format or presentation of the document, it preserves the intended meaning of each element. For example, page headers, sections, paragraphs, etc., are labeled as such in the editing program and displayed appropriately in the browser.^{[citation needed]}