"A widespread myth regarding online advertising is that Google and Facebook are listening to us speak and showing ads on this basis. This is not true, even if it often seems to be. There is a good explanation for this misconception. All of us have probably been part of a discussion on a specific topic—only to see online ads on the same topic immediately afterward. This is not a case of Google recording your speech and using it to target advertising. The most common reason is that people take keener note of matters that they have just discussed. If your phone is showing you ads for holidays in Maui, you probably ignore them. However, if you have just spent time with your cousin in a café, discussing places to visit in Maui during your holiday, the same ad will grab you in a different way. Another explanation is that your friend has been browsing for Internet content relevant to your discussion, even if you haven't. So, if you discussed haggis with your colleagues during your coffee break and you see a Facebook ad for delicious haggis in the afternoon, there is no conspiracy. Inspired by your discussion, your colleague has gone online for a genuine haggis recipe, from the same address space as your workstation. Sometimes, the most peculiar things have perfectly logical explanations."

*If It's Smart, It's Vulnerable", Mikko Hyppönen