When you type google.com into your browser and press Enter, you trigger a sequence of technical processes that happen in milliseconds. Here’s a breakdown of what goes on under the hood, step by step—with Python examples and references.

1. DNS Resolution (Domain Name Lookup)
Your computer must convert google.com into an IP address. This is done through DNS (Domain Name System) resolution. The process involves checking local caches, contacting DNS resolvers, and querying name servers until the IP is found.

Python Example:

import socket
domain = "google.com"
ip = socket.gethostbyname(domain)
print(f"Resolved {domain} to {ip}")

2. Establishing a TCP Connection
Once the IP address is known, your browser uses TCP to connect to Google’s server. A three-way handshake (SYN, SYN-ACK, ACK) sets up the connection.

Python Example:

import ssl, socket
context = ssl.create_default_context()
sock = socket.create_connection((ip, 443))
secure_sock = context.wrap_socket(sock, server_hostname=domain)
print("TCP connection established with Google")

3. TLS Handshake for Secure Connection
Since HTTPS is used, a TLS handshake secures the communication channel. The browser verifies Google's certificate and negotiates encryption protocols.

print(secure_sock.version())

4. Sending an HTTP Request
The browser sends a request for Google’s homepage using the HTTP protocol.

request = "GET / HTTP/1.1\r\nHost: google.com\r\nConnection: close\r\n\r\n"
secure_sock.sendall(request.encode())

5. Receiving and Processing the Response
Google replies with an HTTP response, often a redirect to https://www.google.com.

response = b""
while True:
data = secure_sock.recv(4096)
if not data:
break
response += data
print(response.decode(errors='ignore'))

6. Rendering the Page
The browser processes the HTML, fetches resources (like images and scripts), executes JavaScript, and displays the page.

7. Caching, Cookies, and CDN
Future requests are optimized using cached assets, stored cookies, and data fetched from CDNs (Content Delivery Networks).

Conclusion
Behind the simplicity of entering a URL lies a sophisticated orchestration of systems—networking, security, and rendering—working together to deliver your web experience in real-time.