Font's are usually defined in your document, or more commonly in your CSS file.
Quote:
table td {padding: 0; border-width: 0; vertical-align: top; font-family: Verdana, Arial, Helvetica, sans-serif;}
The font-family property is a prioritized list of font family names and/or generic family names for an element. The browser will use the first value it recognizes.
There are two types of font-family values:
family-name: The name of a font-family, like "times", "courier", "arial", etc.
generic-family: The name of a generic-family, like "serif", "sans-serif", "cursive", "fantasy", "monospace".
You can play areound and change these, but more often times then not, it better to stick with basic fonts. Using a font that you see on your machine may not render on another persons machine because they do not have it installed. There is not 'font' server as it were.
Plain fonts (Arial, Times New Roman, Garamond and Courier) are the easiest to read. Fancy fonts are fine for headings, but not for full pages (imagine trying to read a whole page in Gothic, Script, Westminster, or Cloister). Your eyes would soon tire of the effort involved and you'd be reaching for the back button!
If you want to use custom fonts, it is best to display things with images using the font of your choice however, this will create larger files and longer download times for the user because they are downloading images instead of rendering a font.
Select a font for all your headings and sub-headings (and stick to it). It's not necessary to have a different font for headings (just go up one size for headings, and then use bold on all headings and sub-headings).
This way it's easy to recognise which is a
heading (large and bold) and which is a
sub-heading (same size but bold).
The point of this is to make it easy for your visitors to glance at your page and to take in all the key points. If what they see interests them, they'll stay and keep reading - so it goes without saying, that your headings should be written with care.
The topic in itself is much to involved for one single reply. There are many resources you can use on the web by searching for topics on how to choose a font (or font-family) for your website.
I hope this helps a little bit.