Using Fonts
Fonts are assigned to web pages using the font-family property. This is done using a CSS Rule for the <body> tag. An example of this is:
body {font-family: 'Lucida Sans Unicode', Geneva, sans-serif;}
The font-family property allows a group of fonts to be assigned to cater for different operating systems.
The list above contains a font for Microsoft Windows, Lucida Sans Unicode, one for the Apple OS, Geneva, and a generic font family, sans-serif. The generic font family will be used if the browser doesn't recognise the first two fonts, ensuring the page will display.
W3C on fonts: GO
System Fonts
Operating systems (Windows, Mac) have in-built fonts which browsers can use.
Fonts can be divided into groups or families, Sans-Serif, Serif, Cursive, Monospace, and Fantasy. Fantasy fonts are poorly recognised across browsers and Operating Systems.