Information Technology (IT)
Definition:
The use of computers, networks, software, and other technology to store, retrieve, transmit,
and manipulate data.
Purpose:
● To automate tasks (e.g., payroll systems).
● To communicate globally (email, video calls).
● To manage data efficiently.
● Importance:
● Speeds up business operations.
● Improves accuracy and reduces human error.
● Enables data-driven decision-making.
Why it matters
Lets governments, businesses, schools, and individuals work faster and more accurately.
Makes global communication instant, enabling services such as tele-medicine, streaming,
electronic commerce, and remote work.
Creates entire career paths: network design, application development, technical support,
information-security analysis, data science, and many more.
Advantages
● Dramatic productivity gains, twenty-four-hour availability, rich analytics.
● Easier collaboration across continents.
Disadvantages
● Growing dependence; if systems fail, whole operations can stall.
● Privacy threats and job displacement through automation.
Examples of IT Careers:
Network Engineer — Builds and maintains computer networks.
Software Developer — Creates software applications.
Cybersecurity Specialist — Protects data and networks.
Database Administrator — Manages databases.
Computer Fundamentals
Hardware
Definition: Physical components of a computer system.
Types of Hardware Devices:
Input Devices: Allow users to send data to a computer.
Keyboard: For typing text and commands.
Mouse: Pointing device for GUI navigation.
Scanner: Converts paper documents into digital form.
Microphone: Captures sound.
Webcam: Captures live video.
Output Devices: Present data from the computer to users.
Monitor: Displays images and videos.
Printer: Produces hard copies of documents.
Speakers: Output sound.
Projector: Displays images on a large surface.
Storage Devices: Store data permanently or temporarily.
Hard Disk Drive (HDD): Magnetic storage, large capacity, slower speed.
Solid State Drive (SSD): Flash-based, faster and more durable than HDD.
USB Flash Drive: Portable flash memory device.
Optical Discs (CD/DVD): Use lasers to read/write data, used for backups or media.
Cloud Storage: Internet-based storage services like Google Drive.
Software
Definition: Programs and instructions executed by hardware.
Types of Software:
System Software: Operating Systems (manage hardware & provide interface).
Examples: Windows 10, Linux Ubuntu, macOS Catalina.
Application Software: Programs for user tasks.
Examples: Microsoft Excel, Adobe Photoshop, Google Chrome.
Utility Software: Helps maintain computer performance.
Examples: Antivirus, Disk Cleanup.
Data Types
Integer: Whole numbers (e.g., 7, -15).
Float: Decimal numbers (e.g., 3.14).
String: Text data (e.g., "Hello").
Boolean: True/False values.
Date/Time: Date and time stamps.
Operating Systems (OS)
Definition: Software managing computer hardware and providing services to applications
and users.
Main Functions:
● Process Management: Scheduling tasks.
● Memory Management: Allocating RAM to programs.
● File System Management: Organizing files and directories.
● Device Management: Managing peripherals (printers, scanners).
● User Interface: GUI or Command Line Interface (CLI).
● Security: User authentication and permissions.
Types of OS:
General Purpose: For personal computers (Windows, macOS).
Real-Time OS: Used in embedded systems needing immediate response (e.g., industrial
machines).
Mobile OS: Android, iOS for smartphones.
Server OS: Specialized for managing networks (e.g., Windows Server, Linux Server).
Example:
When you open a program, the OS loads it into memory and allocates resources.
Storage Devices & Types
Primary Storage (Main Memory):
RAM (Random Access Memory): Temporary, volatile memory for running programs.
Cache Memory: Faster, small memory close to CPU for frequently used data.
Secondary Storage:
Used for permanent data storage.
Examples: HDD, SSD, USB drives.
Tertiary Storage:
Used for backups and archiving.
Examples: Optical discs, tape drives.
Cloud Storage:
Internet-based storage accessible anywhere (e.g., Dropbox).
Networking
Types of Networks
Local Area Network (LAN):
Network within a limited area (office, home).
Wide Area Network (WAN):
Covers large areas, connects multiple LANs (e.g., internet).
Metropolitan Area Network (MAN):
Covers a city or campus.
Wireless Networks:
Wi-Fi: Wireless LAN technology.
Bluetooth: Short-range device communication.
Protocols
Transmission Control Protocol / Internet Protocol (TCP/IP):
TCP: Ensures reliable delivery of data packets.
IP: Addresses and routes packets across networks.
Hypertext Transfer Protocol (HTTP):
Protocol used to load web pages on browsers.
Hypertext Transfer Protocol Secure (HTTPS):
Secure HTTP, encrypts data between client and server.
File Transfer Protocol (FTP):
Transfers files between computers over a network.
Simple Mail Transfer Protocol (SMTP):
Used for sending emails.
Database Management Systems (DBMS)
Definition: Software that manages databases.
Components:
Tables: Data stored in rows and columns.
Queries: Retrieve or modify data.
Forms: Interfaces for data entry.
Reports: Organized data summaries.
Structured Query Language (SQL):
SELECT: Retrieve data.
INSERT: Add data.
UPDATE: Modify data.
DELETE: Remove data.
Example:
SELECT Name FROM Employees WHERE Department = 'Sales';
Programming Languages & Software Development
Languages:
Python: Easy syntax, used in AI, web development.
Java: Platform-independent, used in Android apps.
Pascal: Educational, teaches programming basics.
Functions in Programming:
Blocks of reusable code performing specific tasks.
Example: A function to calculate tax based on income.
Spreadsheet Functions:
VLOOKUP: Finds a value in the first column and returns data from another column.
Use: Lookup employee name to get their department.
SUM: Adds numbers in cells.
IF: Executes logic; if condition true, perform action, else do another.
Development Methodologies:
Agile: Flexible, iterative development with frequent feedback.
Waterfall: Linear phases, each completed before next starts.
Web Development
HTML (Hypertext Markup Language):
Defines structure of web pages (headings, paragraphs).
CSS (Cascading Style Sheets):
Styles web pages (color, layout).
JavaScript:
Adds interactivity (click buttons, form validation).
Search Engines:
Programs like Google index web pages for easy search.
Cybersecurity
Malware Types:
Virus: Infects and spreads.
Worm: Self-replicating malware.
Spyware: Collects info secretly.
Ransomware: Encrypts files, demands ransom.
Protection Methods:
● Use strong passwords and change regularly.
● Enable two-factor authentication (2FA) — adds security layer requiring two proofs
of identity.
● Install antivirus software.
● Regularly update systems.
Authentication & Security
Authentication: Process to verify user identity.
Types:
Password-Based: Most common, requires secret text.
Biometric: Uses unique traits (fingerprint, iris).
Two-Factor Authentication (2FA): Password + second proof (SMS code).
Token-Based: Physical or digital token generating codes.
Importance: Prevents unauthorized access to data.
Malware and Virus Protection
Examples:
ILOVEYOU Virus: Spread via email, damaged files worldwide.
WannaCry Ransomware: Locked users’ files demanding payment.
Solutions:
● Regular backups.
● Antivirus scans.
● Avoid clicking suspicious links.
Wireless Communication & Fiber Optics
Wireless:
Wi-Fi for local wireless internet.
Bluetooth for short-range device communication.
Cellular (3G, 4G, 5G) for mobile internet.
Fiber Optic:
Transmits data using light through thin glass fibers.
Advantages: High speed, long distance, low interference.
Ethics in IT
Avoid plagiarism — copying without credit.
Respect user privacy and data protection laws.
Prevent software piracy — illegal copying or use of software.
Responsible disclosure of security flaws.
Biometrics
Identification using unique physical or behavioral traits.
Examples: Fingerprints, facial recognition, voice recognition.
● Used for security and convenience.
Computer hardware building blocks
Component What it does Everyday example Advantage Disadvantage
Central Processing Unit it Executes every arithmetic and logical instruction The
“brain” chip inside a laptopVery fast general-purpose calculation Generates heat,
needs cooling
Random Access Memory Holds data and program code that the Central Processing Unit
is working on right now The temporary space open documents occupy Extremely
quick read-and-writeContents vanish when power is lost
Hard-disk drive Magnetic platter that keeps data even when power is off Desktop
computer with one-terabyte hard disk Cheapest cost per gigabyte Mechanical parts are
slow and fragile
Solid-state drive Stores bits in flash memory chips Modern ultrabook with
five-hundred-gigabyte solid-state drive Fast start-up, no moving parts More
expensive per gigabyte than hard disk
Keyboard (input) Converts keystrokes into digital signals Typing an essay Precise
text entry Slower than speech for long passages
Monitor (output) Converts digital image data into light on a screenWatching a video
lectureRich visual feedbackConsumes desk space and electricity
Storage categories
Primary storage – fast but volatile. Random Access Memory and the smaller on-chip cache
memory keep the working set of a program.
Secondary storage – slower but permanent. Hard-disk drives, solid-state drives, and
portable flash drives keep operating systems, photographs, games, and so on.
Tertiary storage – off-line or near-line media such as magnetic-tape cartridges and optical
discs, mainly for archival backup.
Cloud storage – data kept in huge remote data-centres and accessed through the Internet.
Example: saving coursework files in Google Drive so they can be reached from phone and
laptop alike.
Why different layers exist – Cost, speed, and permanence trade off. Putting everything in
Random Access Memory would be impossibly expensive, while running programs straight
off magnetic tape would be unbearably slow.
Input and output peripherals
● Scanner converts printed pages into digital images—useful for archiving old records.
●
● Web camera captures live video for conferencing.
● Projector throws a computer display onto a large screen for classrooms.
Braille display raises and lowers pins so that blind users can read text output tactilely—an
accessibility triumph but an expensive device.
Software categories
System software
Operating systems coordinate every resource. Examples: Microsoft Windows, Apple
macOS, Canonical Ubuntu Linux (no acronym: Linux is a family name).
Features – memory scheduling, file organisation, user-permissions, graphical desktop,
command-line shell.
Special-purpose operating system – small, highly predictable “real-time” system inside a
pacemaker or an industrial robot; must respond in fractions of a millisecond.
General-purpose operating system – versatile desktop environment that runs word
processors, video-games, and browsers.
Utility programs
Disk defragmenter, backup tool, and antivirus scanner each extend the operating system by
handling maintenance or protection tasks.
Application programs
Everything the end-user launches: spreadsheet, browser, computer-aided-design suite, music
sequencer.
Custom-written software
Bespoke point-of-sale system for a supermarket chain—tailored exactly to its bar-code
scanners and loyalty-card rules; costlier than off-the-shelf packages but can produce
competitive advantage.
Data basics – bits, bytes, and beyond
Bit – the smallest piece of digital information; can hold a zero or one.
Byte – eight bits grouped together; can represent a single keyboard character or part of a
larger number.
Kilobyte – about one thousand bytes; a plain-text page.
Megabyte – about one million bytes; a high-resolution photograph.
Gigabyte – about one billion bytes; a two-hour high-definition film.
Knowing units helps plan storage capacity and download times.
Programming fundamentals
What pseudocode is
Pseudocode is an informal, language-neutral way to write out the steps of an algorithm so
humans can read it easily before committing to real code. Example:
Advantages – very clear syntax, strong data-type checking, helpful for learning good habits.
Disadvantages – limited modern-day library support, less popular for web or mobile
development.
Spreadsheet power
Function VLOOKUP – looks vertically through the first column of a table to match a
search key, then returns a value from another column. Used to pull a student’s grade
automatically when the student name is entered.
Function IF – tests a condition and returns one value if true, another if false, for example
=IF(total>50,"Pass","Fail").
Advantages – quick what-if analysis, simple charts.
Disadvantages – error-prone with very large, formula-dense sheets; not a full relational
database.
Function Full meaning (no acronyms left unexplained) What it does Typical
example Advantages Disadvantages
COUNT(range) Count Numbers – tallies only the cells in a specified range that
contain numerical values =COUNT(B2:B20) returns how many of the cells B2 through
B20 hold numbers • Quick way to see how many sales figures were actually entered•
Ignores accidental text so the tally is purely numeric • Will skip cells that hold dates or
codes stored as text, so total may surprise users
COUNTA(range) Count All – tallies every non-empty cell (numbers and text) in the
range =COUNTA(A2:A20) counts all filled rows in a customer-name column •
Great for finding how many records exist regardless of data type • Simple substitute
for manual row counts • Counts even cells that hold spaces or hidden error messages,
so the result may overstate real records
COUNTIF(range, criterion) Count If Condition Met – tallies cells that match a
single condition you supply=COUNTIF(C2:C100,">=50") counts how many exam marks
are 50 or above • Adds quick one-step filtering without a separate query• Easy to
build descriptive dashboards (e.g., how many orders shipped) • Limited to one criterion;
multiple conditions require COUNTIFS (more complex)
When to choose each
COUNT – whenever you are sure the column contains only numbers and you need a fast
numeric tally (e.g., how many quantities entered).
COUNTA – when the column can hold any type of data and you simply need to know how
many rows are populated (e.g., attendance sheet, roster).
COUNTIF – when you must apply a rule (greater than, equal to, matches text) to see how
many entries satisfy it (e.g., number of “Pending” orders).
Networks
Local Area Network – links computers inside one building with copper or fibre-optic
cabling plus Wireless Fidelity access points.
Metropolitan Area Network – city-wide broadband linking libraries, schools, and
local-government offices.
Wide Area Network – continents-wide connection of Local Area Networks over leased
fibre-optic lines and satellite hops; the Internet is the largest example.
Core device meanings
Router directs data packets toward their destinations by consulting an internal forwarding
table; it joins networks together and decides the next hop.
Switch connects devices inside one Local Area Network and forwards frames only where
needed, reducing unnecessary traffic.
Typical disadvantages of networking
● Susceptible to eavesdropping if data are sent unencrypted.
● Viruses and worms can spread rapidly from one computer to another.
● Installation and maintenance costs (cables, wireless spectrum licences, trained staff).
Communication protocols
Transmission Control Protocol – establishes a connection, numbers every segment, handles
lost packets, guarantees complete delivery.
Internet Protocol – supplies logical numeric addresses so each device can be located;
fragments and routes packets across multiple networks.
Hypertext Transfer Protocol – transfers text, images, and other resources that make up a
web page.
Hypertext Transfer Protocol Secure – wraps Hypertext Transfer Protocol inside Transport
Layer Security encryption so nobody can read or tamper with the content in transit.
File Transfer Protocol – moves whole files between client and server, useful for publishing a
website.
Simple Mail Transfer Protocol – pushes outgoing electronic mail from sender to recipient
servers.
Cyber-threat landscape
ThreatFull meaning How it spreads Impact Counter-measure
Virus - A Malicious code that attaches itself to legitimate files, then executes when the file
is opened Email attachments, pirated software Corrupts or deletes data
Updated antivirus scanner, safe-mail behaviour
Worm -Stand-alone malicious program that replicates across a network without needing a
host file Exploits weak passwords or unpatched services Network congestion, data
theft Timely security patches, firewall blocking
SpywareSoftware -that secretly observes keystrokes or browsing habitsFree “toolbar”
downloads Identity theft, targeted adverts Anti-spyware remover, cautious
installation
Ransomware Program- that encrypts user files and demands payment for the decryption
key Phishing e-mails, remote-desktop attacks Data unavailable, business downtime
Regular offline backups, user education
Meaning of malware – “Malicious software,” any program written with harmful intent.
Passwords and wider authentication
Meaning of password – a secret string known only to the legitimate user, supplied to prove
identity before access is granted.
Why used – simple to implement, compatible with every device.
Disadvantages – people choose weak or reused strings; can be stolen by phishing.
Enhancements – multi-factor authentication requiring something you know (password)
plus something you have (one-time code) or something you are (biometric feature).
Biometric systems explained
Automated Teller Machine with fingerprint reader – ensures that even if someone steals the
bank card, withdrawals still require the rightful owner’s fingertip.
Face unlock on smartphones – faster than typing a passcode and more convenient for
people with disabilities.
Purpose – raise security while improving ease of use.
Concerns – false acceptance or rejection, and privacy if biometric templates are breached.
. Special-purpose versus general-purpose computers
Category Meaning Example hardware Advantage Disadvantage
Special-purpose computer Designed to carry out one task extremely well
Global-positioning satellite control unit, digital-video recorder chipsetHigh efficiency, low
powerCannot be repurposed once manufactured
General-purpose computer Built to run many kinds of program Laptop running
spreadsheet in the morning, video game at night Flexible, software-upgradable
Consumes more power, less optimised
Command-driven interface – user types text commands (for example copy report.txt
d:\backup) into a shell; powerful for experts, steep learning curve for newcomers
Automated Teller Machine (full phrase) technology
What it is – a standalone banking kiosk that dispenses cash and handles basic transactions
by communicating with the bank’s central systems over secure links.
Components – card reader, keypad, cash dispenser, receipt printer, often a fingerprint or
palm-vein sensor.
Purpose – provide twenty-four-hour self-service banking without needing human tellers.
Risks – skimming devices stealing card data, “shoulder surfing” pin theft, network
interception; countered by tamper-evident hardware, encrypted channels, and cameras.
Putting everything together – typical workflow example
A retail chain issues tablets (general-purpose computers) running a custom-written
stock-control application. Staff log in with unique passphrases plus facial recognition.
Tablets connect over a secure Virtual Private Network tunnel, which relies on Internet
Protocol routing and Transport Layer Security encryption, to a central database server. The
server runs Ubuntu Linux and a relational database management system. Daily reports are
exported to a spreadsheet where VLOOKUP pulls each item’s reorder threshold.
Overnight, backups copy the database to an off-site cloud store and also to magnetic tape
for long-term retention. Antivirus signatures and operating-system updates install
automatically. If ransomware were somehow introduced, the offline tape ensures recovery
without paying a ransom.
Absolute referencing (spreadsheets)
What it is: A cell reference that never changes when you copy a formula. You lock it with
dollar signs, like $A$1.
Why it’s needed: Lets you drag formulas across rows/columns but keep certain cells (e.g., a
tax rate in $B$1) fixed, so every copied formula still points to the same constant.
DeviceOne-liner purpose
Server-Powerful computer that stores data or runs services for other devices (clients) on a
network.
Router-Directs traffic between separate networks (e.g., your home LAN ↔ the internet),
choosing the best path for each packet.
Switch-Connects devices inside one local network and sends data only to the intended
recipient port, reducing collisions.
Modem-Converts signals between your ISP’s line (cable, fiber, DSL) and digital data your
router/switch can use.
Data theft
Unauthorized copying, transfer, or retrieval of personal, financial, or proprietary
data—think stolen credit-card numbers, leaked customer databases, or swiped trade secrets.
Backing up data – the essentials
External drive (offline)
Copy important folders to a USB or external HDD/SSD.
Use built-in tools (Windows File History, macOS Time Machine) for automatic, versioned
backups.
Cloud backup
Services like Google Drive, OneDrive, iCloud, Dropbox, or dedicated backup apps
(Backblaze, Carbonite) sync your files to encrypted storage online.
Disk-image / system backup
Creates a full snapshot of your entire drive—including OS and apps—so you can restore
everything after a crash.
Windows – “Backup & Restore (System Image)” / macOS Time Machine / Linux tools like
Clonezilla.
3-2-1 rule
Keep 3 copies of your data
on 2 different media
with 1 copy off-site (cloud or another location).
Website vs. web page
Term What it is Analogy
Web page A single document you view in a browser, with its own unique URL. One
page in a magazine.
Website A collection of related web pages under one domain (plus images, scripts,
etc.).
