I think they do, but it's not compulsory for a Visitor to click ads on your site. If a visitor visits your site but leaves no click no worries, there no harm in it
Yes, they Google may collect information about your visitors, which is why you need to state that in your privacy policy. From the Google Terms and Conditions: https://www.google.com/adsense/localized-terms
Yes Google tracks the IP address of the visitors visiting the site.( Google tracks mnay other things which we don't know e.g our computer harware serial numbers and alot more things) Some time when the same visitors clicks many times on the ads Google counts them as invalid clicks.
They probably do it, but what I don't understand is that I have a friend from my neighbourhood, he is clicking everyday on his own google ads and he is making money from it... Last week he made $50... And still not disabled from google adsense ! I think google is too busy to detect it or they cancel the accounts when people make lots of money doing like that..
Give it time, they'll eventually send him a warning and annul the earnings or even suspend the account. You don't cheat G, G cheats you
Yes.. Google tracks all the IP address from which the Ads are displayed whether clicked or not. 1. To show Ads localized to your Region/Country/State Based on IP address. 2. For the purpose of statistics. 3. To check whether the Ads are displayed on the publisher's computer (Google recommends publishers not to use the pages too much which has their own Ads as this makes increased impressions, It also recommends not to refresh the pages unnecessarily for the same reason.) So if you are having AdSense on Website, place the Ads only after completing the editing as you may need to refresh your site if you are using online editors. Not only Google, most of the Average to Big companies analyze the IP from their logs. They use software to analyze it.. Sometimes they even do manual lookup if found eccentric . It helps you to know to which place do your visitors belong and how did they land into your site and many more. Even me also go through the Visitor Logs in my website stats..
I would like to add that if you have the Analytics code on your website,they will also track visitors.