How the Internet Actually Works: From Your Device to the Server

Source: Dev.to

What Is a Network?

A computer network is a group of connected devices that communicate with each other to share data and resources. It enables efficient communication and supports services like email, file sharing, and Internet access.

Lay‑man’s definition

Computers + Wires/Wireless + Protocol = Network
Protocol – a set of rules for formatting and processing data.

The Internet – A Network of Networks

When multiple networks are connected together, we call the resulting system the Internet.
The Internet is a global system of interconnected computer networks that uses the Internet Protocol Suite (TCP/IP) to communicate between networks and devices.

Lay‑man’s definition

Network of Networks = Internet

To understand how the Internet reaches your home, we need two fundamental concepts:

1. Packets – the small segments a message is broken into for transmission.
2. Protocols – the rules that define how those packets are formatted and processed.

Packets

• A packet contains data (the actual message) and metadata (information about the data).
• The metadata is stored in the header, which describes characteristics of the data.
• When data is sent over the Internet, it is split into packets, converted to bits, and routed by networking devices (routers, switches, etc.).
• At the destination, the receiving device reassembles the packets in the correct order to reconstruct the original message.

Packets travel very fast.

Protocols

In networking, a protocol is a standardized way of performing actions and formatting data so that two or more devices can communicate and understand each other. Because all Internet‑connected devices implement these protocols, the Internet works regardless of who or what connects to it.

Physical Infrastructure That Makes the Internet Work

Below is a quick overview of common networking devices. Each description is followed by a diagram (click the image to view the full‑size version).

Hub

A hub connects multiple computers in a Local Area Network (LAN). It has many ports but cannot filter traffic; any incoming data is broadcast to every port.

The receiving machine processes the data; all others discard it, which can waste bandwidth.

Bridge

A bridge connects multiple LANs (the process is called bridging). It learns MAC addresses, divides networks into smaller segments, and typically has two ports.

Switch

A switch divides a network into multiple subnets and forwards packets based on MAC addresses. It filters traffic, so only the intended recipient receives each packet.

Router

A router connects two or more IP networks (or subnets) and acts as a doorway between your local network and the Internet. It enables multiple devices—computers, smartphones, tablets—to share a single Internet connection.

Modem

A modem (modulator‑demodulator) translates digital signals from your computer into analog signals for transmission over physical lines, and vice‑versa, allowing the device to communicate with the wider Internet.

Firewall

A firewall is a network‑security device that regulates incoming and outgoing traffic based on predefined security rules, protecting the network from unauthorized access and malicious activity.

Load Balancer

A load balancer distributes incoming traffic across multiple servers, providing high availability, efficient resource utilization, and improved performance.

Summary

When you send a request from your device, it does not go directly to the internet or the server. The journey typically follows these steps:

1. Local switch – The request first reaches a switch inside your local network. The switch forwards data to the correct device within the same network (e.g., your router) based on MAC addresses.
2. Router – Moves data between different networks, directing your request toward your ISP and the wider internet.
3. Modem – Converts the digital data to an analog signal before it leaves your premises.
4. Firewall (optional) – Inspects traffic and decides whether to allow it based on security rules.
5. Internet backbone – The request traverses multiple intermediate routers across the internet until it reaches the destination network.
6. Load balancer (optional) – Distributes the request among several servers, selecting the one that will handle it.
7. Server – Processes the request and sends a response back through the same path in reverse.

The above flow shows how a simple request on your device traverses various network components before reaching its final destination and how the response follows the same route back to you.