Network: Computers and devices connected to share data
LAN: Local area network, such as in a home or school
WAN: Wide area network that spans a large area
Internet: A global network of networks
Intranet: A private network inside an organization
IP address: A number that identifies a device on a network
IPv4 address: Four numbers 0 to 255, like 192.168.1.1
IPv6 address: A longer address format with letters and numbers, made for more devices
Public IP: An address visible on the internet
Private IP: An address used inside a local network, like 192.168.x.x
Localhost (127.0.0.1): Your own computer
MAC address: A hardware address built into a network card
DNS: Domain Name System, translates names into IP addresses
DHCP: Automatically gives devices IP addresses
NAT: Lets many devices share one public IP address
Router: Forwards data between networks
Switch: Connects devices within a network
Hub: A simple device that repeats data to all ports
Modem: Connects a home to the internet provider
Access point: Gives wireless devices a connection to a network
Gateway: A node that connects one network to another
Firewall: Controls which traffic is allowed in or out
Proxy server: A server that acts as middleman for requests
VPN: Virtual private network that sends traffic through an encrypted tunnel
Protocol: A set of rules for communication
TCP: Reliable, ordered delivery of data
UDP: Fast delivery without guarantees, used in streaming and games
IP (Internet Protocol): Addresses and routes packets
HTTP: Protocol for web pages
HTTPS: HTTP with encryption
FTP: Protocol for transferring files
SMTP: Protocol for sending email
IMAP and POP3: Protocols for receiving email
SSH: Secure remote login
TLS/SSL: Encryption protocols for secure connections
Port: A numbered door on a device for a type of traffic
Port 80: HTTP
Port 443: HTTPS
Port 22: SSH
Port 25: SMTP email
Port 53: DNS
Packet: A small chunk of data sent over a network
Header: Information at the start of a packet like source and destination
Latency: Delay before data arrives
Bandwidth: Maximum data rate of a connection
Throughput: The actual data rate achieved
Ping: Test of reachability and round-trip time
Traceroute: Shows the path packets take
Jitter: Variation in delay
Packet loss: Packets that never arrive
Wi-Fi: Wireless local networking
Ethernet: A common wired network standard
Fiber optic: Cables that send data as pulses of light
Cellular (4G, 5G): Mobile phone networks
Bluetooth: Short-range wireless
Subnet: A smaller part of a network
Subnet mask: Tells which part of an address is the network
CIDR notation: Writing a network like 192.168.0.0/24
Client: A device that requests services
Server: A device that provides services
Peer-to-peer: Devices share directly without a central server
Cloud: Computing services offered over the internet
CDN: Content delivery network, servers around the world that make sites load faster
URL: A web address
Domain registrar: A company that sells domain names
ICANN: The organization that coordinates domain names and IP addresses
Web server: Software that serves web pages
API: Rules for programs to talk to each other
REST: A common style for web APIs
Status code 200: OK
Status code 404: Not found
Status code 500: Server error
Status code 301: Moved permanently
OSI model: A seven-layer model of networking
OSI layers: Physical, Data Link, Network, Transport, Session, Presentation, Application
TCP/IP model: A four-layer model that the internet uses
Three-way handshake: SYN, SYN-ACK, ACK to start a TCP connection
Vint Cerf and Bob Kahn: Designed TCP/IP in the 1970s

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