Every website you visit can track you — not just through cookies (which you've seen those annoying banners about) but through browser fingerprinting. Your browser leaks your screen size, installed fonts, system settings, and dozens of other signals that together create a unique identifier. You can be recognized across sites even in private browsing mode.
Four things to do right now: First, install uBlock Origin (free, open source). It blocks ads, trackers, and malicious scripts. On Chrome, Firefox, and Edge. This is the single highest-impact browser privacy change available.
Second, in your browser privacy settings, set tracking protection to 'Strict' (Firefox) or enable 'Block third-party cookies' (Chrome/Safari). This stops sites from communicating with data brokers in the background.
Third, use a privacy-respecting search engine. Google tracks every query. DuckDuckGo, Brave Search, or Startpage search Google's index without storing your queries. DuckDuckGo is the easiest switch — same results, no profile.
Fourth, clear cookies monthly or use your browser's 'delete cookies on close' setting. Better yet, consider Firefox with the Facebook Container extension, which isolates Facebook tracking to its own container so it can't follow you around the web.
If you want to go further: Brave browser has all of this built in by default with no configuration required. It's Chrome-compatible (same extensions, same engine) and blocks fingerprinting natively.