Unwanted pop-ups?

Having been plagued this week at the point of 'check-out' on a well-known commercial website, despite Adblock, I now, as an aged person operating beyond their computer-Apple-literacy limits, know exactly what it's like to have these unsolicited intrusions into my privacy as per Nenny 512...'s post. Convinced by some of the Apple community (thank you so much!) that these are not a virus, but simply a con-device, I, in desperation, uploaded the latest OS software 'High Sierra' for my equally ageing computer - and it has finally blocked them. So, it's not a question, merely a hopefully up-to-date helpmeet to any one else in the same position :-)