Since website coding began html has not been friendly towards the usage of custom fonts this meant a set of web safe fonts was developed in standard html to include san serifs: Arial, helvetica, Verdana, Tahoma, Geneva, Impact, Charcoal, Comic Sans MS and serif fonts: Georgia, times, palatino and book antiqua. These fonts are the most common typefaces preinstalled with computer system software.
However this has now changed with the introduction of googles new web fonts: https://www.google.com/fonts
Now you can insert a vast array of typefaces via their free service. Also by adding some CSS code to reference the service you are no longer reliant on the viewer having the particular typeface installed on their computer.