Most small to medium sized companies do not have a connection to the internet. The main reason is the restriction placed on technology or lack of it within their organization. Access to the internet is guarded, knowledge is power in the computer community, it is expensive and may be technologically beyond the capabilities of a small company. Traditionally to hook to the internet you will need a Unix workstation and a Unix knowledgeable computer operator, these computers very a great deal from a DOS based PCs. Costs associated with the internet connection can be found elsewhere in this document.
Domain names are an integral part of the Internet addressing.
All correspondence over email must contain domain names for both the sender and receiver. You can think of domain names being kind of a postal address, where the city, state and zip code are all rolled into one word. The domain name in the address ensures that the email will be routed to the proper place. This name may include a hyphen and is limited to 12 letters, numbers and symbols may not be used. Similar to a postal address, Internet email addresses are all unique.