What it is: Connecting two or more computers/devices to share resources (data, printers, internet connection, etc.).

Core Concepts:

• Nodes/Hosts: Devices connected to the network (computers, servers, printers, etc.).
• Links/Cables: The physical or wireless connections between nodes.
• Network Interface Card (NIC): Hardware that allows a device to connect to a network.
• Protocols: Rules that govern how data is transmitted and received (TCP/IP, HTTP, DNS, etc.).
• IP Address: A unique numerical identifier assigned to each device on a network.
• MAC Address: A unique hardware address assigned to each NIC.

Network Topologies (Physical Layouts):

• Bus: All devices connected to a single cable (obsolete).
• Star: All devices connected to a central hub or switch (most common).
• Ring: Devices connected in a closed loop (rare).
• Mesh: Each device connected to multiple other devices (high redundancy).

Network Types (Based on Size/Scope):

• LAN (Local Area Network): Connects devices in a limited area (home, office).
• WLAN (Wireless LAN): LAN using wireless technology (Wi-Fi).
• MAN (Metropolitan Area Network): Connects devices in a city or metropolitan area.
• WAN (Wide Area Network): Connects devices across a large geographical area (the internet).

Key Protocols (TCP/IP Suite):

• TCP (Transmission Control Protocol): Reliable, connection-oriented protocol.
• IP (Internet Protocol): Handles addressing and routing of data packets.
• HTTP (Hypertext Transfer Protocol): Used for web browsing.
• HTTPS (HTTP Secure): Secure version of HTTP.
• DNS (Domain Name System): Translates domain names (e.g., google.com) to IP addresses.
• DHCP (Dynamic Host Configuration Protocol): Automatically assigns IP addresses to devices.

Key Devices:

• Router: Connects different networks and forwards data packets between them.
• Switch: Connects devices within a LAN.
• Hub: (Obsolete) Connects devices within a LAN, but less efficient than a switch.
• Firewall: Protects a network from unauthorized access.

Network Model (OSI Model):

A conceptual framework that divides network communication into seven layers:

1. Application: (HTTP, SMTP) – User interface.
2. Presentation: (Encryption, Compression) – Data format.
3. Session: (Manages Connections) – Establishes, manages, and terminates connections.
4. Transport: (TCP, UDP) – Reliable/Unreliable data transfer.
5. Network: (IP) – Routing data packets.
6. Data Link: (Ethernet) – Provides error-free transmission between adjacent nodes.
7. Physical: (Cables, Wireless) – Transmits raw data bits.

Security Fundamentals:

• Firewalls: Control network traffic.
• VPNs (Virtual Private Networks): Securely connect to private networks over the internet.
• Encryption: Protect data confidentiality.

In short: Networking is all about connecting devices and allowing them to communicate. Understanding protocols, network topologies, and key devices is crucial for building and maintaining networks.