2. LAN LAN is abbreviation of Local Area Network. It is network that can use general facilities level. If we use this, We can use Internet and etc without a lot of cable. This is very convinient system.

3. VPN Virtual Private Network is a virtual computer network, that is usually called to VPN. The purpose of a VPN is to allow communications between systems connected to the VPN using an existing shared to as a VPN Tunnel. Secure VPNsare designed to provide information security features such as authentification and confidentiality and are often used to secure traffic travelling over the Internet.

4. ISDN Integrated Services Digital Network (ISDN) is a set of communications standards for digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network.

6. ISP An Internet service provider (ISP) is a company that offers its customers access to the Internet. The ISP connects to its customers using a data transmission technology appropriate for delivering Internet Protocol datagrams, such as dial-up, DSL, cable modem, wireless or dedicated high-speed interconnects.