If you use the Avast Antivirus program, you may have read that a subsidiary of Avast -- Jumpshot -- harvests data from your web browsing and sells it to advertisers. The following article explains more:
https://lifehacker.com/use-these-antivirus-and-anti-malware-apps-instead-of-av-1841264690
I've used Avast for years, and have been pleased with it. But this news makes me reconsider what AV program I might use instead. Right now I'm looking at Bitdefender Antivirus, which gets good ratings in AV tests.
Just something for you to be aware of.
Jim Hamm