How the Internet Works

The internet is a global network of interconnected computers using the TCP/IP protocol.

Key Concepts

• IP Address — unique device identifier
• DNS — domain name resolution
• TCP/UDP — transport protocols
• HTTP/HTTPS — web protocols

Syntax

COMPUTER-SCIENCE

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# Request flow
Browser → DNS → IP → TCP → Server → Response

# Ports
HTTP: 80 | HTTPS: 443 | SSH: 22

HTTP Request Concept

PYTHON

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# HTTP request concept (simulated)
import json

# Simulate an HTTP request
request = {
    "method": "GET",
    "url": "/api/users",
    "headers": {
        "Content-Type": "application/json",
        "Authorization": "Bearer token123"
    }
}

response = {
    "status": 200,
    "headers": {"Content-Type": "application/json"},
    "body": json.dumps({"users": ["Alice", "Bob"]})
}

print("Request:")
print(json.dumps(request, indent=2))
print("
Response:")
print(json.dumps(response, indent=2))

Try It Yourself

Practice

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Exercise

What happens when you type a URL in the browser?

Answer

DNS resolves domain to IP, browser sends HTTP request to server, server responds with HTML, browser renders it.

Quick Quiz

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What port does HTTPS use?

80

443

22

3306

HTTPS uses port 443. HTTP uses port 80.

Retry Quiz

Interview Questions

What is the difference between TCP and UDP?

TCP is reliable and ordered. UDP is faster but unreliable. TCP for web/email, UDP for gaming/streaming.

Next Lesson

OSI Model