Contacts are key people associated with accounts. A contact can only belong to one account, however, a contact may be associated with multiple opportunities. Your access to contact information is determined by your access rights to that contact's account. You always have access to your personal contacts.
You can view contact information either on an Account or Opportunity Tab, in a list of query results, or on the Contact Detail view. When working with contacts, you may want to schedule activities, or run processes to help you work with and manage your contacts as efficiently as possible.