Short answer
Fingerprinting can use user agent, screen, language, time zone, fonts and other signals to recognize a browser.
Why fingerprinting works
Each signal is often common, but the combination can be more unique. This makes tracking possible even when cookies are blocked.
What you can reduce
Use an updated browser, limit unnecessary extensions, block third-party tracking and choose privacy modes that reduce variation.
What VPN does not change
VPN changes the IP address but normally not the browser fingerprint. VPN and fingerprinting may therefore need separate handling.
Common questions
Is fingerprinting the same as cookies?
No. Cookies are stored in the browser. Fingerprints are calculated from properties the browser exposes.
Can I stop all fingerprinting?
It is difficult, but you can reduce detail and variation.