A Man-in-the-Middle (MITM) attack is when someone secretly sits between two people (or computers) who are talking and listens to or changes the messages without them noticing.

How it works

When your computer connects to a website, data travels through many steps across the network. In a MITM attack, the attacker places themselves in that path. They can read your data, steal things like passwords, or even alter the message before passing it along. To both sides, it looks like a normal conversation, but it's actually being spied on.

Analogy

Imagine you write a letter to a friend. A sneaky person intercepts it, opens it, reads it, maybe changes some lines, then sends it on. Your friend thinks the letter came straight from you, but in reality, it was tampered with on the way. That's what a MITM attack does online.