Local Area Network (LAN): A LAN is a computer network that interconnects devices within a small geographic area, such as a single building or a campus. Virtual Local Area Network (VLAN): A VLAN is a network that logically separates devices into different broadcast domains, even though they are physically connected to the same network infrastructure. Wide Area Network (WAN): A WAN is a computer network that covers a large geographic area, such as a city, state, or country. Storage Area Network (SAN): A SAN is a specialized high-speed network that provides block-level access to data storage. Wireless Local Area Network (WLAN): A WLAN is a LAN that uses wireless communication, such as Wi-Fi, to connect devices. Internet: The Internet is a global network of computers connected through the Internet Protocol (IP). Extranet: An extranet is a private network that is partially accessible to authorised external parties, such as customers or partners. Virtual Private Network (VPN): A VPN is a private network that is created by using public communication infrastructure, such as the Internet. Personal Area Network (PAN): A type of computer network that is used for personal or individual use, typically covering a small area such as a home, office or small group of offices. Peer-to-Peer (P2P): A type of network architecture where each node is capable of acting as both a client and a server, allowing data to be shared directly between nodes without the need for a central server. OSI Seven Layer Model: The Open Systems Interconnection (OSI) Seven Layer Model is a theoretical model that describes how data is transmitted between networked devices. The seven layers are: Physical, Data Link, Network, Transport, Session, Presentation, and Application. Physical Layer: The lowest layer of the OSI model, responsible for transmitting and receiving raw bitstreams over a physical medium, such as copper wire, fiber optic cable, or wireless transmission. Data Link Layer: The layer responsible for the reliable transfer of data between two adjacent nodes on a network. This layer is responsible for error detection and correction, and can also manage flow control. Network Layer: The layer responsible for routing data between different networks. This layer is responsible for addressing and routing data packets between networks, and can perform functions such as fragmentation and reassembly. Transport Layer: The layer responsible for reliable end-to-end communication between applications running on different hosts. This layer provides services such as connection-oriented or connectionless data transmission, flow control, and error recovery. Session Layer: The layer responsible for establishing, managing, and terminating communication sessions between applications. This layer manages the dialogue between applications, and can also provide services such as checkpointing and recovery. Presentation Layer: The layer responsible for representing data in a format that can be understood by applications. This layer can perform functions such as data encryption and decryption, compression and decompression, and data formatting. Application Layer: The highest layer of the OSI model, responsible for providing application services to users. This layer includes all the protocols and services that support applications, such as email, file transfer, and web browsing. Protocol: A set of rules and guidelines that govern the communication between devices on a network. Data Packet: A unit of data that is transmitted over a network. A packet typically contains a header with routing information and a payload with the actual data being transmitted. Packet Switching: A method of transmitting data in which packets are sent individually over a network and reassembled at the destination. Circuit Switching: A method of transmitting data in which a dedicated circuit is established between the sender and receiver. Speed of Data Transmission: The rate at which data is transmitted over a network, typically measured in bits per second (bps). Data Compression: A technique used to reduce the size of data being transmitted over a network, allowing for more efficient use of network resources and faster transmission times. Transmission Media: The physical medium through which data is transmitted over a network. Examples include metal conductors (such as copper cables), fibre optic cables, wireless (such as Wi-Fi or WiMAX), and others. Wireless Networks: A type of network that uses wireless transmission media (such as Wi-Fi or WiMAX) to connect devices, allowing them to communicate without the need for physical cables. Changes in Working Patterns: Refers to shifts in the way people work, such as increased telecommuting, remote work, and flexible work arrangements. These changes have been driven by advancements in technology and the availability of high-speed Internet connectivity. WiFi: A popular wireless networking standard that is used to connect devices such as computers, smartphones, and tablets to the Internet or to local networks. Worldwide Interoperability for Microwave Access (WiMAX): A wireless networking standard that provides high-speed Internet connectivity over long distances. Network Security: The set of technologies, processes, and practices designed to protect a network and its associated devices from unauthorised access, use, disclosure, disruption, modification, or destruction. Encryption Types: Methods used to scramble data so that it can only be decrypted and read by authorised parties. Examples include symmetric encryption, asymmetric encryption, and hash functions. Data Integrity: The accuracy, completeness, and consistency of data during transmission, storage, and retrieval. Flow Control: A technique used to regulate the flow of data between two devices or systems in order to prevent data loss or buffer overflow. Deadlock: A situation that occurs when two or more processes or devices are waiting for each other to release resources, resulting in a standstill or system failure. Congestion: A situation that occurs when a network or communication channel becomes overloaded with data traffic, resulting in slower data transmission or even data loss. Error Checking: A technique used to detect errors in data transmission, storage, and retrieval. This can involve various methods, such as parity checking, checksums, or cyclic redundancy checks (CRC).