There are literally thousands of fonts available, but one never knows which of the many are installed on the user's devices.  A few, however, are designated "websafe fonts" because they are almost universally installed.  Those fonts fall into five broad categories, as follows:

SERIF FONTS:

Times New Roman

Georgia

Palatino

Book Antiqua

SANS SERIF FONTS

Arial

Helvetica

Geneva

Lucida Sans Unicode

MONOSPACE FONTS

Courier New

Monaco

Lucida Console

CURSIVE FONT(S)

Comic Sans MS

FANTASY FONT(S)

Impact

Now let's see if I can make them appear!  JB 2/29/12.