I am trying to build a website that will have promotional offers and I would like to ask the specialists in here if what I want is possible. Let's call my site A Another site - C
A visitor goes to website C then comes to website A. Is it possible for me to know that he visited website C before coming to my website ( presuming ofcourse he hasn't used a tool like ccleaner to empty his browsing history ). Knowing this I could display a message like. Our price is 5% lower than site C. Also another limited way would be to read the tab of the browser? If user has site C and site A open in the same time, in the same browser I could view that he visits both in the same time? I am open to all solutions that would allow me to do this. Initially I thought it's possible through local storage in html5 but upon reading I start to think it's not. However I just started studying and will look further.