In the context of a web browser, a frame is a part of a web page or browser window which displays content independent of its container, with the ability to load content independently. The HTML or media elements in a frame may come from a web site distinct from the site providing the enclosing content. This practice, known as framing, is today often regarded as a violation of same-origin policy. In HTML, a frameset is a group of named frames to which web pages and media can be directed; an iframe provides for a frame to be placed inside the body of a document. Since the early 2000s, concern for usability and accessibility has motivated diminished use of framesets and the HTML5 standard does not support them.

Tags and attributes

The frames in HTML are created using the tag pair. The tag is a container tag for all other tags that are used to create frames. The tag replaces the tag in frameset documents.The tag defines how to divide the window into frames. Each frameset defines a set of rows or columns. If user define frames by using the attribute then horizontal frames are created. If user define frames by using then vertical frames are created. The element may be included so web browsers with frames disabled (or browsers that do not support frames) can display something to the user, as in this example: Framesets have a attribute. If set to an integer greater than 0, the user can resize the frames by dragging this border, unless a attribute is present in a frame element. If border is set to 0, no border will be displayed and content in different frames will abut each other without delineation. The element is used inline within a normal HTML body, and defines the initial content and name similarly to the element. Any text inside an tag pair will be displayed in browsers that do not understand the iframe tag.

History

Netscape Navigator 2.0 introduced the elements used for frames in March 1996. Other browser vendors such as Apple with Cyberdog followed later that year. At that time, Netscape proposed frames to the World Wide Web Consortium (W3C) for inclusion in the HTML 3.0 standard. Frames were used to display and navigate early online magazines and web apps, such as webmail services and web chat sites. Frames had the advantage of allowing elements to be displayed sitewide without requiring server features such as server-side includes or CGI support. These features were not common on early web servers accessible to the public. Early websites often used a frame at the top to display a banner which could not be scrolled away. These banner frames sometimes included the site's logo as well as advertising. XHTML 1.1, the intended successor to HTML 4, removed all frames. XFrames, the intended eventual replacement, provided the composite URI to address a populated frameset. The later HTML5 standard removed framesets by means differing from XHTML. The element remains with a number of "sandboxing" options intended for sharing content between sites.

Advantages

By allowing content to be loaded and navigated independently, frames offered several advantages over the plain HTML in use when they were first developed:

Criticism

The practice of framing HTML content led to numerous criticisms, most centering on usability and accessibility concerns. These include:

Security

Frames create both technical and user-interface difficulties for enforcement of the same-origin policy. As an example of the latter, an outer page can trick a user into performing an action on an inner page (loaded using the iframe element) which has been made 99% transparent.

Alternatives

As web technology developed, many of the purposes for which frames were used became possible in ways that avoided the problems identified with frames.