Deprecated HTML tags
In its earliest incarnation, HTML was a language used both to structure information and lay it out visually on web pages. As such, it originally contained a number of tags meant only to format the look of text (e.g., font color and size) without imparting information about its structural intent (for example, heading levels or hyperlinks).
With the advent of CSS (Cascading Style Sheets), information about the look of text was separated into a specific style sheet language. This enabled the removal of complicated text formatting tags within HTML documents, and freed HTML to focus on its core task as a markup language defining the structure (and not the appearance) of web pages. As stated by the W3C (World Wide Web Consortium, the standards body that maintains HTML and CSS):
HTML has its roots in SGML which has always been a language for the specification of structural markup. As HTML matures, more and more of its presentational elements and attributes are being replaced by other mechanisms, in particular style sheets. Experience has shown that separating the structure of a document from its presentational aspects reduces the cost of serving a wide range of platforms, media, etc., and facilitates document revisions.
This doesn’t mean, however, that most browsers can’t still read depreciated tags (that is, tags no longer recommended by the W3C). Here’s an example of two deprecated tags that merely (and badly) describe only the appearance, and not the structure of text:
The first of two notoriously outdated tags reminiscent of amateur 1990’s web design, the blink tag (which blinks text on and off like a neon sign) tells you nothing about the purpose of the text within it.
Similarly, the marquee tag merely creates an (annoying) scrolling text effect, without providing information about the proper place or purpose of the text within a document.
Other depreciated tags include font tags that change the color and size of text (these have been replaced by CSS font properties) and tags like center that indicate only the look of text on a page and not its purpose.
A reference for current HTML 4.1 tags in use comes in handy when first learning to assess the quality of HTML code on the web, which is useful to do if you plan to use or copy existing code yourself.