Visual contrast and page design
Good typography depends on the visual contrast between one font and another, and the contrast between text blocks and the surrounding empty space. Nothing attracts the eye and brain of the viewer like strong contrast and distinctive patterns, and you only get those attributes by carefully designing them into your pages. If you make everything bold, then nothing stands out and you end up looking as if you are SHOUTING at your readers. If you cram every page with dense text, readers see a wall of gray and their brains will instinctively reject the lack of visual contrast. Just making things uniformly bigger doesn't help at all. Even boldface fonts become monotonous very quickly, because if everything is bold then nothing stands out "boldly."
Use the major HTML headings sparingly. One alternative to overly bold HTML headers is to use the physical style controls of HTML to make text bold or italic without increasing the font size. However, you should understand that there are some disadvantages to using physical styles to control the typography of your Web pages. The HTML heading tags (H1, H2, etc.) are designed to identify important titles and subtitles in your text, and are only incidentally meant to change the visual display of the titles. If you use the "FONT SIZE" tags in Netscape and use physical styles like "BOLD" then automatic indexing and text analysis programs will have a difficult time analyzing your web documents.
Visual logic versus structural logic
The framers of the original HTML standards were physical scientists who wanted a standard means to share documents with minimal markups aimed at revealing the logical structure of the information. Since they had little interest in the exact visual form of the document, no precise typography and page formatting is possible in current implementations of HTML. In focusing solely on the structural logic of the HTML document, the framers of the Web ignored the need for the visual logic of sophisticated graphic design and typography.
The standards organization responsible for codifying the HTML language is responding the widespread complaints of graphic designers that the heading tags in Web documents often produce clunky, over-large titles and subtitles. Through style sheets and new font control tags future versions of HTML will soon allow you to specify what size font each header level will produce in each Web page. Thus you will be able to produce more sophisticated typography without giving up the substantial advantages of using the conventional HTML header tags.
Type and legibility
We read primarily by recognizing the overall shape of words, not by parsing each letter and then assembling a recognizable word:
Your choice of uppercase or lowercase letters can have a dramatic effect on legibility. In general, use downstyle (capitalize only the first word, and any proper nouns) for your headlines and subheads. Downstyle headlines are more legible, because we primarily scan the tops of words as we read: