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The Magic Behind Your Browser: What Happens When You Type in a URL

Alright, so you’re browsing the web, and you type in https://www.google.com and hit enter. But do you have any idea what happens behind the scenes to bring you the web page you requested? Let’s take a closer look.

What Happens When You Type in a URL

DNS Request

First, your browser sends a request to a DNS (Domain Name System) server to translate the domain name into an IP address. The DNS server looks up the IP address associated with the domain name and sends it back to your browser. This process is known as DNS resolution and is critical to accessing websites.

TCP/IP

Once the IP address is obtained, your browser establishes a connection with the server using TCP (Transmission Control Protocol) to send and receive data. TCP breaks data into small packets, which are sent over the internet and reassembled on the receiving end. This ensures that data is transmitted reliably and accurately.

Firewall

But wait, before the connection is made, a firewall steps in to check the incoming traffic and make sure it’s not malicious. This is like a bouncer at the door, keeping the riff-raff out. Firewalls use a set of rules to allow or block incoming traffic based on factors like IP address, port number, and protocol.

HTTPS/SSL

Next up is HTTPS (Hypertext Transfer Protocol Secure) and SSL (Secure Sockets Layer) negotiation. This ensures that any data transmitted between your browser and the server is encrypted and secure. That means your sensitive information, like your passwords and credit card details, are kept safe from prying eyes.

Load-balancer

If the website is hosted on multiple servers, a load-balancer distributes incoming traffic across those servers to prevent overload. Think of it like a traffic cop, making sure the servers don’t get overwhelmed.

Web Server

The web server processes the request and sends back the HTML, CSS, and JavaScript files that make up the web page. The HTML contains the structure and content of the web page, while the CSS controls the presentation and layout, and the JavaScript adds interactivity and functionality. The web server also sets cookies, which are small text files stored on your computer that contain information about your browsing session.

Application Server

If the website has any fancy features, like a search function or a login system, an application server processes those requests and sends back the relevant info to the web server. Application servers can run complex code and interact with databases to provide dynamic content. They often run on separate servers from the web server to improve performance and scalability.

Database

And finally, if the requested info isn’t stored on the application server, the server sends a request to the database to retrieve the data. The database then sends back the requested info to the application server, which then sends it to the web server. It’s like a game of telephone, but with data. Databases store and organize large amounts of data and are essential for websites that have a lot of content or require user data storage. Below is a simple schema illustrating the processes mentioned above. You can view the full image here.

In summary, loading a web page is a wild and complex process involving all sorts of technology and magic. Understanding how it all works can help you troubleshoot any issues you might run into while browsing the web. So go forth and browse with confidence, knowing that your trusty browser and its army of servers have got your back!

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