CSC 227
INTRODUCTION TO
INFORMATION
PROCESSING
FOCUS FOR TODAY
● PRINCIPLES OF DATA
COMMUNICATION.
● THE INTERNET AND THE WORLD
WIDE WEB (WWW).
Data communication refers
to the exchange of data
between two or more
devices through a
transmission medium.
DATA COMMUNICATION
For communication to occur,
the devices must share a
common language known as
a protocol. This ensures that
the sending and receiving
systems understand each
other.
Fundamental Principles of Data Communication
1. Delivery: Data must be delivered to the correct destination. This is achieved
through addressing systems, like IP addresses, that identify the intended
recipient.
2. Accuracy: Data must arrive at its destination without being corrupted. Protocols
with error detection and correction mechanisms ensure data integrity.
3. Timeliness: For time-sensitive data like video or voice, data needs to arrive
within a specific timeframe to be useful. Delays can lead to a poor user
experience.
4. Protocol: This is the most fundamental principle. A protocol is a set of rules that
governs data communication. Both the sender and receiver must use the same
protocol to communicate successfully.
While security is very important in modern communication, it is considered an additional
requirement, not a core fundamental principle in the traditional sense.
Components of a Data Communication System
A typical data communication system has five essential components:
1. Message – The actual data being communicated (text, images,
audio, video).
2. Sender – The device that sends the message (computer,
smartphone).
3. Receiver – The device that receives the message (another
computer, printer).
4. Transmission Medium – The pathway over which data travels
(cable, fiber optics, radio waves).
5. Protocol – The set of rules that govern communication (TCP/IP,
HTTP).
Data Transmission Modes
● Simplex – Data flows in one direction only.
Example: Keyboard to computer, TV broadcast, Projector
Radio, PA system.
● Half-Duplex – Data flows in both directions, but only one at
a time. Example: Walkie-talkies.
● Full-Duplex – Data flows in both directions simultaneously.
Example: Telephone calls , Video Conferencing, Online chat
etc.
What is a Signal?
A signal is basically the physical form in which information
travels from one place to another.
It’s the “messenger” carrying the data over a communication
medium (like wires, fiber optics, or air).
● In wired communication → the signal is a change in electric
voltage or current.
● In wireless communication → the signal is a change in
radio waves, light, or microwaves.
Role of Signal in Data Communication
Data communication is all about sending data from a sender to a receiver.
The process looks like this:
1. Data: Raw information (text, numbers, images, etc.).
2. Encoding: Converting data into a signal format that can travel through a medium.
3. Transmission: Sending that signal over the medium.
4. Reception & Decoding: The receiver detects the signal and converts it back to
data.
Without signals, the data would just sit in your computer — it needs a physical form to
travel.
Types of Signals
● Analog signals are continuous waves that vary in
amplitude or frequency.
Example: Traditional radio broadcasts.
● Digital signals use discrete binary values (0s and 1s).
Example: Computer network data.
Digital communication is generally preferred for its accuracy,
security, and ease of error correction.
Transmission Media
Guided media – Physical pathways such as:
● Twisted-pair cables (Ethernet cables)
● Coaxial cables (TV cables)
● Fiber optic cables (high-speed internet)
Unguided media – Wireless transmission such as:
● Radio waves (Wi-Fi, FM radio)
● Microwaves (satellite communications)
● Infrared (remote controls)
Networking Devices
Used to connect multiple computers or networks.
● Hub → Simple device that broadcasts data to all connected
devices (rare in modern networks).
● Switch → Smarter than a hub; sends data only to the
intended recipient device (between the same network).
● Router → Connects different networks (e.g., home network
to the Internet) and directs data packets.
Network Topologies
The arrangement of network devices:
● Bus – All devices connected to a single cable.
● Star – All devices connected to a central hub.
● Ring – Devices connected in a closed loop.
● Mesh – Devices interconnected with multiple
paths.
● Hybrid – Combination of topologies.
Communication Protocols and
Standards
Protocols ensure reliable and standardized
communication:
● TCP/IP – Internet communication
● HTTP/HTTPS – Web browsing
● FTP – File transfers
● SMTP – Email
Performance Metrics
● Bandwidth – Maximum data transfer
capacity of a medium (measured in bits per
second).
● Latency – Delay between sending and
receiving data.
● Throughput – Actual data transfer rate
achieved.
The Internet
The Internet is a global network of
interconnected computer networks
(network of networks). It's the physical
and logical infrastructure that allows
data to be transmitted between any two
points in the world.
Basic Internet Infrastructure
The Internet is made possible by a combination of hardware and
software components:
1. Internet Service Providers (ISPs) – Companies that provide
Internet access to users (e.g., MTN, Glo, Airtel in Nigeria).
2. Routers – Devices that direct data packets between networks.
3. Servers – Powerful computers that store and deliver web pages,
emails, and files.
4. Clients – User devices like smartphones, laptops, or tablets that
request information from servers.
5. Transmission Media – Cables, satellites, and wireless links that
carry data.
Internet Protocols
Protocols are rules that allow devices to communicate. Common
Internet protocols include:
● IP (Internet Protocol): Identifies devices using IP addresses.
● TCP (Transmission Control Protocol): Ensures reliable delivery
of data.
● UDP (User Datagram Protocol): Sends data without
error-checking, useful for streaming.
● HTTP (Hypertext Transfer Protocol): Transfers web pages.
● HTTPS (Secure HTTP): Transfers web pages securely with
encryption.
● FTP (File Transfer Protocol): Transfers files between computers.
Domain Name System (DNS)
DNS is the phonebook of the Internet. It translates
human-friendly domain names (e.g., www.example.com) into
IP addresses (e.g., 192.168.1.1) that computers can
understand.
● Domain name: Easy-to-remember name for a website.
● IP address: Numerical label used to locate a device on a
network.
Without DNS, users would have to remember long strings of
numbers instead of website names.
Web Browsers and Search Engines
● Web Browsers: Applications that display web pages
(e.g., Chrome, Firefox, Safari, Edge).
● Search Engines: Tools that help locate information
on the Internet by indexing web content (e.g.,
Google, Bing, Yahoo).
Browsers interpret HTML, CSS, and JavaScript to
present a user-friendly interface, while search engines
use algorithms to rank and display relevant results.
The World Wide Web: Concepts and Architecture
The World Wide Web (WWW) is a collection of linked documents
and resources connected by hyperlinks, accessible via the Internet.
● Client-server architecture: The browser (client) requests a web
page from a server.
● Hyperlinks: Allow navigation between pages.
● HTTP/HTTPS: Used to transfer data between browser and
server.
The WWW is just one part of the Internet — email, instant
messaging, and file transfers also run on the Internet but are not part
of the WWW.
Web Technologies
● HTML (Hypertext Markup Language): Structures
web content.
● CSS (Cascading Style Sheets): Styles the look and
layout of pages.
● JavaScript: Adds interactivity and dynamic features.
Together, these form the foundation of modern
websites.
Trends and Future of the Internet
● Internet of Things (IoT): Everyday objects connected to
the Internet.
● 5G networks: Faster speeds and lower latency.
● AI integration: Smarter search engines, automated
chatbots.
● Virtual & Augmented Reality: Immersive online
experiences.
● Blockchain: Decentralized record-keeping for secure
transactions.
THANK YOU AND
GOD BLESS
