As the name suggests, the meaning of hub is a center of activities. In network terminology, a hub is a device where the entire connecting mediums come together.
Network security barrier. A firewall is a device that guards the entrance to a private network and keeps out unauthorized or unwanted traffic. When people talk about a corporate or enterprise firewall, they normally assume a series of devices guarding all points of entry, thus creating a secure environment "behind" or "inside" the firewall -- as distinct from the untamed and lawless territory that lies "beyond" or "outside"
An extranet is a private network that uses Internet technology and the public telecommunication system to securely share part of a business's information or operations with suppliers, vendors, partners, customers, or other businesses. An extranet can be viewed as part of a company's intranet that is extended to users outside the company.
Generic name for a family of fast digital communication services such as asymmetric digital subscriber Line (ADSL), symmetrical digital subscriber line (SDSL), and very high rate digital subscriber line (VDSL).
communication can be split into two parts -- the message or content, and the channel it's transmitted on. For example, you may want to communicate something about your emotional state -- let's say that you are angry.
