🌐 Web Applications
📌 1. Definition
A Web Application is a software program that runs on a web server and is accessed through a web browser over the internet or intranet.
👉 Users do not need to install it locally; they only need a browser.
🎯 2. Key Idea
User → Browser → Internet → Web Server → Application → Response
✔ Everything runs online using a browser interface.
🧠 3. Components of Web Application
1. 🖥️ Client (Front-End)
-
Runs in browser
-
Built using:
✔ Responsible for user interface
2. ⚙️ Server (Back-End)
3. 🗄️ Database
-
Stores data permanently
-
Examples:
📊 4. Web Application Architecture
👉 Draw this in exam:
Client (Browser)
↓
Web Server (PHP / JSP / ASP.NET)
↓
Database (MySQL, etc.)
↓
Response → Browser
🧩 5. Types of Web Applications
1. 📄 Static Web Applications
- Fixed content
- No database
- Example: simple portfolio website
2. 🔄 Dynamic Web Applications
- Content changes based on user input
- Uses database
- Example: Facebook, Gmail
3. 🛒 E-commerce Applications
- Online shopping systems
- Example: Amazon, Daraz
4. 🏢 Enterprise Web Applications
- Large business systems
- Example: ERP systems
5. ☁️ Single Page Applications (SPA)
- Loads single page, updates dynamically
- Example: Gmail, Google Maps
⚙️ 6. Characteristics of Web Applications
- Platform independent
- Runs on browser
- Requires internet/intranet
- Centralized data storage
- Easy updates
📈 7. Advantages
- No installation required
- Accessible anywhere
- Easy maintenance
- Centralized updates
- Cross-platform support
❌ 8. Disadvantages
- Requires internet connection
- Security risks
- Performance depends on network
- Browser compatibility issues
🔐 9. Security in Web Applications
Common threats:
- SQL Injection
- Cross-Site Scripting (XSS)
- Data theft
Protection methods:
- Encryption (HTTPS)
- Authentication
- Input validation
📊 10. Web Application vs Website
| Feature |
Web Application |
Website |
| Interaction |
High |
Low |
| Function |
Dynamic |
Static |
| Data |
Database used |
Limited |
| Example |
Gmail |
Blog site |
🧠 11. Web Application Workflow
User Input → Request → Server Processing → Database → Response → Display
⚠️ 12. Important Rules
✔ Always validate user input
✔ Use secure communication (HTTPS)
✔ Optimize for performance
✔ Ensure responsive design
✔ Handle errors properly
❓ 13. Likely Exam Questions
Short Questions
- Define web application.
- What are components of web application?
- What is client-server architecture?
- Define dynamic web application.
- What is database in web apps?
Long Questions
- Explain web application architecture with diagram.
- Discuss types of web applications.
- Explain advantages and disadvantages of web applications.
- Differentiate web application and website.
- Describe security issues in web applications.
📝 14. Summary / Quick Revision
👉 Web applications are the foundation of modern internet services like Gmail, Facebook, and online banking.