Explore computer networks, the internet, web browsers, email, Google Apps, and modern digital devices used in today's offices and classrooms.
Data Communication is the process of transferring digital data between two or more devices through a transmission medium (wired or wireless). For communication to occur, both sender and receiver must use the same communication protocol.
The device that originates and sends data. Example: your computer, phone.
The path through which data travels. Cable (wired) or air/radio waves (wireless).
The device that accepts and processes the incoming data.
Agreed rules for data exchange. Examples: TCP/IP, HTTP, FTP, SMTP.
Fig 7.1 — Network types by geographic coverage
| Network Type | Full Form | Coverage | Examples |
|---|---|---|---|
| LAN | Local Area Network | Single building or campus (up to a few km) | School computer lab, office floor, home network |
| MAN | Metropolitan Area Network | A city or large campus (up to 50 km) | City government network, university campuses, cable TV networks |
| WAN | Wide Area Network | Countries or worldwide | The Internet, bank ATM networks, railway reservation systems |
| PAN | Personal Area Network | A few metres (person's reach) | Bluetooth headset, smartwatch connected to phone |
| VPN | Virtual Private Network | Any distance (secure tunnel over Internet) | Remote work connections, secure government networks |
| Feature | LAN | WAN |
|---|---|---|
| Coverage | Limited (building/campus) | Very large (country/world) |
| Speed | Very high (100 Mbps – 10 Gbps) | Slower (varies, 1 Mbps – 1 Gbps) |
| Setup Cost | Low | High |
| Ownership | Privately owned (one org) | Multiple orgs / ISPs |
| Technology | Ethernet, Wi-Fi | Leased lines, satellites, fibre optic |
| Error Rate | Low (short distance) | Higher (longer paths) |
| Example | Office network, college lab | Internet, BSNL, Airtel backbone |
The Internet is a global network of millions of interconnected computers and devices that communicate using the TCP/IP protocol. It originated from ARPANET (USA, 1969) and became publicly available in the early 1990s. Today it connects over 5 billion users worldwide.
Uses of the Internet: Communication (email, chat, video calls), information retrieval (websites, Wikipedia, news), entertainment (YouTube, streaming), e-commerce (shopping, banking), e-governance (income tax, TNPSC applications), education (e-learning, COA study), and cloud storage (Google Drive, OneDrive).
URL (Uniform Resource Locator) is the address of a specific page or resource on the internet.
Example: https://www.tndte.gov.in/coa-results
https:// — Protocol (secure HTTP) | www — subdomain | tndte.gov.in — domain name | /coa-results — path to the page
| Domain Extension | Used By | Examples |
|---|---|---|
.com | Commercial organisations | google.com, amazon.com |
.gov / .gov.in | Government websites | tndte.gov.in, india.gov.in |
.edu / .ac.in | Educational institutions | iit.ac.in, anna.ac.in |
.org | Non-profit organisations | wikipedia.org, who.int |
.net | Network / internet providers | bsnl.net, airtel.net |
.in | India-specific websites | flipkart.in, irctc.co.in |
Uses ordinary telephone line and a modem. Very slow, ties up the phone line. Largely obsolete. Still used in very remote areas.
Integrated Services Digital Network. Faster digital telephone lines. Two channels: 64 Kbps each (128 Kbps combined). Used before broadband became common.
Digital Subscriber Line. Uses phone line but doesn't block calls. ADSL (Asymmetric DSL) is the most common home broadband type. Provided by BSNL, TATA.
Uses the same coaxial cable as cable TV. High speeds. Shared with neighbours so speed may vary. Provided by Hathway, ACT Fibernet.
Light pulses through glass/plastic fibre. Fastest wired connection available. Used by BSNL FTTH, Jio Fibre, ACT Fibernet. Increasingly common in cities.
Wireless LAN using radio waves (IEEE 802.11). Range: 30–100m. Used in homes, offices, cafes. Wi-Fi 6 reaches 9.6 Gbps theoretically. Router connects to ISP.
Wireless MAN technology. Range up to 50 km. Used for last-mile connectivity in areas where cable is not feasible.
Internet via satellite in space. Available anywhere — deserts, oceans, remote mountains. High latency (delay). Used by ships, aircraft, military, rural areas. StarLink is a modern example.
Internet through mobile networks. 4G LTE: up to 100 Mbps. 5G: up to 10 Gbps. Used by smartphones and hotspot devices. Providers: Jio, Airtel, Vi.
World Wide Web (WWW) is a system of interlinked web pages and resources accessed through the Internet using a web browser. It was invented by Tim Berners-Lee in 1989 at CERN, Switzerland. The Web uses HTTP/HTTPS protocol and HTML language.
| Term | Meaning |
|---|---|
| Website | A collection of related web pages under one domain. E.g., tndte.gov.in |
| Web Page | A single document viewable in a browser (HTML file with text, images, links). |
| Homepage | The default starting page of a website, usually the first page that opens. |
| Hyperlink | Clickable text or image that navigates to another page or resource. |
| HTTP | HyperText Transfer Protocol — rules for transferring web pages. Port 80. |
| HTTPS | Secure HTTP using SSL/TLS encryption. Shown by the padlock 🔒 in the browser. Port 443. |
| HTML | HyperText Markup Language — the language used to create web pages. |
| IP Address | Unique numerical address of a device on the internet. E.g., 192.168.1.1 (IPv4). |
| DNS | Domain Name System — converts domain names (google.com) to IP addresses. |
| Downloading | Transferring a file from a remote server to your computer. |
| Uploading | Transferring a file from your computer to a remote server or website. |
A Web Browser is application software used to access, navigate, and display web pages from the Internet. It communicates with web servers using HTTP/HTTPS protocol and renders HTML content visually.
Most popular. Developed by Google. Fast, supports extensions, syncs with Google account. Developer tools built in.
Open-source browser. Known for privacy features and customisation. Good for developers and privacy-conscious users.
Built into Windows 10/11. Based on Chromium. Integrates with Microsoft 365, Bing AI assistant. Replaces Internet Explorer.
Default browser on Mac and iPhone/iPad. Fast, energy efficient. Not available on Windows or Android.
Fast browser with built-in VPN, ad blocker, and battery saver mode. Popular on mobile devices.
Privacy-focused browser. Blocks all ads and trackers by default. Chromium-based. Fast loading.
A Search Engine is a web service that indexes millions of web pages and finds the most relevant results for a user's query. It uses web crawlers (bots) to scan and index websites continuously.
| Search Engine | URL | Special Feature |
|---|---|---|
| google.com | Most powerful; AI features; Image, News, Maps, Scholar search | |
| Bing | bing.com | Microsoft's search engine; Copilot AI integrated; image creator |
| Yahoo | yahoo.com | Portal with news, email, finance; powered by Bing search |
| DuckDuckGo | duckduckgo.com | Privacy-first — does not track user searches or profile users |
| Baidu | baidu.com | Dominant search engine in China; Chinese language optimised |
Effective Search Tips: Use specific keywords ("COA exam results 2026"), use quotes for exact phrases ("computer on office automation"), add site: to search within a site (site:tndte.gov.in results), use filetype: to find documents (COA syllabus filetype:pdf).
Email (Electronic Mail) is a method of exchanging digital messages over the internet. It is fast, free, and reliable. An email address has two parts separated by @: username@domain.com (e.g., student.coa@gmail.com).
Dear Sir/Madam,
Please find attached the official notification and examination centre schedule for the COA February 2026 examination. Kindly take necessary action and communicate the same to all concerned institutes in your district.
Regards,
Joint Director
Directorate of Technical Education
Open browser → type mail.google.com or gmail.com → click "Create account".
Type your First Name, Last Name → choose a Gmail address (e.g., yourname2026@gmail.com) → create a strong password (8+ characters, mix of letters, numbers, symbols).
Enter your phone number → Google sends a 6-digit OTP via SMS → enter OTP to verify.
Enter date of birth, gender → agree to Google's Terms of Service and Privacy Policy → Click "I agree".
Your Gmail inbox opens. Your email address is now active and can send/receive emails globally.
| Operation | How to Perform | Notes |
|---|---|---|
| Compose / Write | Click "+ Compose" (Gmail) → fill To, Subject, Body → Send | Compose new email to anyone with an email address |
| Read Email | Click the email in Inbox to open it | Unread emails are in bold. Click to mark as read. |
| Reply | Open email → click Reply (↩) → type response → Send | Replies go only to the sender |
| Reply All | Click "Reply All" — responds to sender AND all recipients in To and CC | Be careful — reply all sends to everyone! |
| Forward | Open email → click Forward (↪) → enter new recipient → Send | Sends the email to someone not in the original list |
| Attach File | Compose → click 📎 (paperclip) icon → browse and select file → Open | Max attachment size: 25 MB in Gmail. Use Google Drive link for larger files. |
| Save Email | Click the star ⭐ to mark important. Or move to a Label/Folder. | Starred emails are saved in "Starred" folder |
| Print Email | Open email → click ⋯ (More) → Print → Ctrl+P | Prints email with header details and attachments list |
| Delete Email | Select email → click 🗑 or press Delete → email moves to Trash | Trash is auto-emptied after 30 days |
| CC (Carbon Copy) | Enter email addresses in the CC field | CC recipients receive the email and everyone can see they received it |
| BCC (Blind Carbon Copy) | Click BCC → enter addresses in BCC field | BCC recipients are hidden from other recipients — used for privacy |
| View Attachment | Open email → click the attachment file name → opens in preview or downloads | Scan attachments with antivirus before opening unknown files |
| Filter / Organise | Gmail Settings → Filters → create rules to auto-label, archive, or forward emails | Filters automatically sort incoming mail |
Security Tip: Never open attachments from unknown senders. Never share your email password with anyone. Always log out of your email on shared computers. Enable 2-Step Verification (2FA) for extra security — even if someone has your password, they cannot access your account without your phone.
Google Workspace (formerly G Suite) is a collection of free, cloud-based productivity applications by Google. All apps work in a web browser — no installation required. Data is saved automatically to Google Drive and accessible from any device.
Go to forms.google.com (sign in with Google account if prompted) → click "Blank form" or choose a template.
Click "Untitled form" → type a title (e.g., "Student Feedback Form"). Add a description explaining the form's purpose below the title.
Click the + button on the right toolbar → choose question type: Short answer, Paragraph, Multiple choice, Checkboxes, Dropdown, Date, Time, or File upload. Type the question text.
Toggle the "Required" switch on each question that must be answered. Required questions show a red asterisk (*).
Click "Send" (paper plane icon) → share via email link, or copy the shareable URL. Respondents submit without needing a Google account (if set to public).
Click "Responses" tab → see summary charts, individual responses. Click "Link to Sheets" to send all responses to a Google Sheet for analysis.
| Feature | Google Docs | Google Sheets | Google Slides |
|---|---|---|---|
| Equivalent to | MS-Word | MS-Excel | MS-PowerPoint |
| File format | .gdoc (native), .docx | .gsheet, .xlsx | .gslides, .pptx |
| Create | docs.new or drive → New → Google Docs | sheets.new | slides.new |
| Share & Collaborate | Click "Share" → add email addresses → set Viewer/Commenter/Editor permission | Same | Same |
| Download | File → Download → .docx, .pdf, .txt | File → Download → .xlsx, .csv, .pdf | File → Download → .pptx, .pdf |
| Auto-save | Every few seconds to Google Drive | Same | Same |
| Offline use | Enable in Chrome (Docs offline extension) | Same | Same |
| Version History | File → Version History → see all edits and restore any version | Same | Same |
Modern offices and executives use a variety of digital devices beyond the desktop computer. Understanding these devices helps you work efficiently in any government or private office environment.
Turn on the scanner. Ensure it is connected to the computer (USB or Wi-Fi). Check that the scanner driver is installed (Device Manager → Imaging Devices).
Lift the scanner lid → place document face-down on the glass, aligned to the corner markers → close the lid gently.
Search for "Windows Fax and Scan" in Start menu → click "New Scan" → select scanner → choose document type (Photo/Document) → set resolution (300 DPI) → set file type (PDF or JPEG).
Open "Simple Scan" from Applications → select scanner → click Scan → choose Document or Photo mode → adjust settings.
Click "Preview" to see a thumbnail first. Adjust crop area if needed. Click "Scan" (full quality scan). Wait for the scan to complete.
After scanning: use Windows Photos or Paint to crop, rotate, adjust brightness/contrast, and save as a different format.
Save scan to a folder (e.g., Desktop → Scanned Documents). Name the file descriptively (e.g., Receipt_April2026.pdf). Now ready to upload to e-Office as a Receipt.
google.com → press Enter Step 1mail.google.com → click "Create account" → follow Gmail registration steps Create Accountforms.google.com → click "Blank form" Step 1docs.new → a blank document opens automatically Step 1sheets.new → Rename the file "Student Marks Sheet 2026" Step 1=C2+D2 → press Enter → drag fill handle down to E6 Step 4 — Formula=IF(E2>=40,"Pass","Fail") → drag down → share with teacher Step 5slides.new → choose a theme from the "Choose a theme" panel Step 1ScannedPhoto_Edited.jpg to Desktop → task complete Step 51. LAN stands for:
2. The World Wide Web was invented by:
3. In an email, BCC stands for:
4. Which internet connection type uses light pulses through glass fibres for the fastest speeds?
5. What does the padlock 🔒 symbol in a browser's address bar indicate?
6. Google Forms responses are automatically linked to which Google application?
7. The recommended scan resolution for official documents is:
8. URL stands for:
9. Match — Which keyboard shortcut opens a new Incognito window in Google Chrome?
10. True or False: All Google Workspace apps (Docs, Sheets, Slides) automatically save your work to Google Drive — no manual saving is required.