Can clearify what you mean "leaves tracking pixels" how are you seeing this or where is it at?

regular cookies can easily be eliminated but some sites or links hide pixels on the computer to follow the user, even when the cookies are erased.

That's not how pixels work, tracking pixels are simply just images on a website that show the website that the image was downloaded. They aren't stored on your computer except in your cache

Hi, thanks for your insight. At one time I came across some kind of link that showed how I could use to locate the pixels and be able to delete them or not as I wished. What you are suggesting is that emptying the cache would solve this.? Or can I selectively do that

and see which sites are doing it?

I'd suggest using some tools to protect your privacy, one i use is called uBlock Origin, https://addons.mozilla.org/firefox/addon/ublock-origin/

You can set network.cookie.thirdparty.sessionOnly to true on the about:config page to make third-party cookies behave as session cookies that expire when Firefox is closed.

You can open the about:config page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue.

• http://kb.mozillazine.org/about:config

your description sounds like it could be effective on windows, however on a mac or ipad i dont know how to access the corresponding functions