Choosing the right typeface for your website is crucially important if you are to succeed on the internet, as some font types are more easily readable than others, and some are more widely available.
You want to choose font types that are: (a) Suit the character of your site, (b) Are easy to read on a computer screen, and (c) Are widely available across many browsers and operating systems.
There are basically two types of fonts: serif and sans serif. Serif fonts are those that have fine cross-lines at the extremities of the letter. Sans serif ("sans" being the French word for "without") are fonts that don't have serifs. The most common serif font is probably Times New Roman. Arial is an example of a common sans serif font.
Let's go briefly through the most popular font types and evaluate their availability, readibility and character:
Arial
Availability: Widely available. It is probably the most common sans serif font. It is the default font for Windows, and it first shipped as a standard font with Windows 3.1.
Readability On Screen: Not the worse but definitely not the best, especially at small sizes, when it becomes too narrow and the spacing between characters too small.
Character: Has a streamlined, modern look but is also plain and boring. *For Mac users, the equivalent of Arial is Helvetica.
Times New Roman
Availability: Widely available. It is probably the most common serif font. It is the default font for web browsers. It was first shipped as a standard font with Windows 3.1.
Readability On Screen: Acceptable for font sizes of 12pt. and up, but terrible for smaller sizes.
Character: Serious, formal and old fashioned. *For Mac users, the equivalent of Times New Roman is Times.