Security on the web varies from one person to the next.
Protecting valuable information from prying eyes is imparitive.

It may be interpreted as barring some visitors from certain areas of your site, such as a members-only area, or a login system for other web services.

Or it might mean ensuring that a credit card transaction
does not make the credit card holder's card number available to unauthorized parties.

• Security Policy
  Document each facet involved in protecting the server and the directories that reside on it.
  
  
• Configuration
  Maintaining the proper server configurations and the various server applications that may reside on the website's host machine.
  
  
• Authentication
  Administer areas of a website that are open to some but not all: Administrative areas, members-only areas and staff-only areas are commonly protected directories found on sites.
  
  
• Access
  Administer access to only those directories and files that will be needed by a given user. That is, if a user needs to maintain only a specific file or directory on the server, then restrict that user to the specified directory.