This in-depth guide explains how browser fingerprinting silently tracks users by collecting hundreds of device attributes such as screen size, WebGL data, fonts, and IP addresses to build unique digital identities. Unlike cookies, fingerprinting cannot be deleted and allows websites or advertisers to recognize you across sessions. Learn the difference between active and passive fingerprinting, real-world tests comparing Chrome, Brave, Mullvad, and Tor, and how privacy-focused browsers defend against tracking. Discover key protection strategies such as standardization vs randomization, blocking third-party scripts, using tools like uBlock Origin and NoScript, enabling anti-fingerprinting in Firefox, and adopting browsers like Tor, Brave, or Mullvad. The guide also explores privacy implications, legal contexts, and the future of cross-device tracking and anti-detection technologies in 2025.