People use "privacy" to mean at least three different things. Conflating them leads to bad decisions, like using Tor to hide from an abusive partner who has access to your unlocked phone.
Privacy
Privacy is control over who sees your information and activity. A sealed letter is private: the postal service knows who is writing to whom, but not what was said. You can have privacy without anonymity. Your bank knows exactly who you are, but your transactions should still be hidden from everyone else.
Security
Security is the ability of a system to resist unauthorized access. It is what keeps an attacker from reading the data you decided to store. Security is a prerequisite for privacy (an insecure messenger cannot be a private one) but it is not the same thing. Google services are highly secure. They are not private from Google.
Anonymity
Anonymity is the separation between your activity and your real identity. A whistleblower posting documents needs anonymity; whether the documents are encrypted in transit matters less than whether the post can be traced back to them. Anonymity is the hardest property to achieve and the easiest to destroy: a single login from the wrong network, one reused username, one payment with a linked card can collapse it permanently. The Darwin Awards section is largely a catalog of people learning this.
Why the distinction matters
Each property calls for different tools and different behavior:
| You want | Example goal | Typical measures |
|---|---|---|
| Privacy | Keep your medical searches out of ad profiles | Private browser settings, encrypted DNS, a trustworthy search engine |
| Security | Keep your accounts from being taken over | Password manager, MFA, device updates |
| Anonymity | Publish something without it being attributed to you | Tor, strict compartmentalization, clean devices |
Most people reading this site need privacy and security. Few need anonymity, and pursuing it half-heartedly is worse than not pursuing it at all, because it produces false confidence. Decide which property you actually need using threat modeling, then invest accordingly.