The internet is something we use every day for everything, so it's important to understand how information is transferred through it. On the internet, data is broken into small packets, and each packet travels through different routes to reach its destination.

Why is data broken into packets? → Because networks can be unreliable. Sometimes, due to technical issues, connections may drop, causing data in transit to be lost. To prevent this, we break data into parts. There are other reasons too, like efficiency. If we split data into packets, each packet can take a different path and reach the destination faster. This is known as packet switching. Transferring a whole block of data can cause network congestion, which is inefficient. It also helps us check for errors since each packet has its own error-checking mechanism, known as checksum or CRC (Cyclic Redundancy Check). If one network is down, packets can reroute their path, which is known as having no single point of failure.

What does one packet contain? →

Header: Tells routers how and where to send it
Data: The actual stuff (e.g., “Hi”, or a chunk of image/video)
Trailer: Checks if the packet was corrupted

1. WhatsApp Message

When you send a message, it is converted into bytes and packed into TCP packets. Each packet includes headers (IP, port, sequence number) and is sent to WhatsApp’s server. The server receives these packets, reassembles them in order based on the sequence number, and then forwards them to the receiver.

2. Instagram Photo Upload

The photo file is divided into multiple TCP packets, usually about 1500 bytes each. Each packet includes the file offset (sequence) so the server knows where it belongs. If a packet is lost or arrives corrupted, TCP requests a retransmission. Once all packets are received, the server rebuilds the complete image.

3. YouTube Video Streaming

YouTube sends video data in chunks using either TCP or a protocol like HTTP/3 (over QUIC/UDP). Each chunk is made of packets that contain video frames. If a packet is lost during UDP-based streaming, it’s skipped to maintain playback speed. The player buffers a few seconds ahead to keep the stream smooth.

4. Online Game (e.g., Valorant)

Game clients send player input (e.g. movement, shooting) to the server via UDP packets for low latency. These packets are small and frequent. Since UDP doesn’t guarantee delivery, some lost packets are acceptable, as the game state keeps updating rapidly with new input.

5. Gmail Email Sending

When you send an email with an attachment, the entire content is encoded and divided into TCP packets. These are sent over the internet with error checking and ordering handled by TCP. The Gmail server receives the packets, verifies integrity, and stores the complete email for delivery.

Everything you do online sending messages, watching videos, or playing games works by breaking data into small packets. These packets travel across the internet and are reassembled at the other end. It's fast, reliable, and the reason the internet works so smoothly today.

Exploring the Basics of Internet Data Transfer