Most ad providers (as well as social media sites) use third-party cookies to track your activity around the Internet. This is why I use Firefox, which has a number of privacy features built in. They now block third-party cookies by default:
https://support.mozilla.org/en...
I also use a Firefox addon called AdNauseum, which serves to hide ads and "click" on every single one. This has the effect of corrupting the ad servers' datasets (since they think you click on every ad, over time this results in a loss of any clear trends). It also means that sites that depend on advertising still get revenue from the "clicks".
https://adnauseam.io/
It can be installed on Chrome, but it's a lot harder as Google has blocked it by default (which is understandable as it impacts their advertising model).
If you have a Google account, you can also opt-out of Google's ad personalisation:
https://support.google.com/ads...
With all of these in place, I can't recall seeing any personalised ads for a long time.
