A good web site is one that meets its business objectives. Okay, that's obvious. How does a web site become successful and reach its business objects? Form and function. The site has to function to meet the user needs of gathering information, being entertained, or placing an order. The site form should be usable, and maybe even pleasing to the user.
Form
Form is the graphic design of a web site. Colors, fonts and graphics used to set the tone of the web site.
Function
Function is the information architecture of a web site. Information architecture is the organization of information in a web site. It includes the navigation between pages and forms.
When creating a web site or having someone create a web site for your business, it is easy to get caught up in how it looks. Remember that function is just as important. You know your business and your customers. What will they be looking for on your web site?