Understanding Computer Networks

• A computer network allows two or more computers to communicate.

Network Communication Rules

• Protocols are communication rules that ensure messages are successfully transmitted, such as the use of "@" in email addresses.
• "http://" or "https://" is necessary for web addresses.

Network Hardware

• Network cables connect devices, using plastic plugs and copper wires to send data in both directions.
• Hubs connect multiple computers together via ports for cable connections.
• Routers connect networks over large areas, forwarding messages and acting as gateways; they commonly link home networks to the internet via an ISP.
• A server is a powerful computer offering services, such as a file server storing files accessible to all network devices.

Network Connection Types

• Wired connections transmit data using ethernet cables.
• Wireless connections transmit data through the air using radio waves, such as Bluetooth, WiFi, 4G, and 5G.

Bandwidth and Data Transfer

• Bandwidth is the amount of data transferable from one point to another in a specific time; higher bandwidth means more data per second.
• Bandwidth is measured in bits per second (bps).
• At today's data transfer rates, bandwidth is typically measured in Megabits per second (Mbps), where 1 Mb equals 1 million bits.
• Buffering occurs when data arrives slower than it's processed, indicating a need for more bandwidth.

Internet Infrastructure

• The internet is a global network of computers involving physical hardware like cables and routers.
• Ocean internet cabling transmits 99% of internet data between continents.

Data Transmission

• Networks send and receive messages in packets, which are small data units.
• A large message splits into multiple packets, each containing a part of the message and the sender/receiver IP addresses.
• An IP address is unique for every device on the internet.
• Internet Protocol (IP) is a protocol to route the packets, and each device has a unique IP address.
• TCP splits messages into packets and reassembles them in the correct order at the receiving end.

Digital Footprint

• A digital footprint is all online information about an individual, including website visits, emails, and information submitted to online services.
• Metadata is "data about data," referring to additional information exchanged by apps and devices, often without the user's knowledge.
• A privacy policy explains how an organization handles personal information.
• A packet 'header' contains the Sender IP address, Receiver IP address, total number of packets, the sequence number of this particular packet

Privacy and Security

• Privacy, in the context of the internet, means controlling who can see or use your information.
• Keylogging is recording a user's keystrokes to gain fraudulent access.
• Malware includes software intended to damage or control a computing system.
• Phishing attempts to trick users into providing personal information to access sensitive online resources.

Encryption

• Encryption encodes messages to keep them secret, allowing only authorized parties to read them.
• Decryption reverses encryption to reproduce the original text.
• Cipher is a generic term for a technique or algorithm that performs encryption
• Caesar Cipher shifts the alphabet by some number of characters for encryption.
• Cracking encryption attempts to decode a secret message without knowing the specifics of the cipher.
• Random substitution cipher matches every letter of the alphabet to a random different letter of the alphabet.

Authentication

• Single factor authentication requires only one element of secrecy
• Two factor authentication that requires two elements of secrecy
• Multifactor authentication that requires three or more elements of secrecy

Types of Malware

• A computer virus is malware that spreads between computers and damages data and software.

Explore the fundamentals of computer networks, including communication protocols like HTTP and network hardware such as routers and servers. Learn about wired (Ethernet) and wireless (WiFi) connection types and the concept of bandwidth in data transfer. Understand how these components facilitate seamless communication between devices.