Website targeted advertising...how does it work?
The other day I was looking on JL: website and looked at some bathroom scales (yes yes post -Xmas excess!) and television bargains. Today I look at a completely unrelated website and between articles there is an advert that flashes up from JL with the exact same scales and TVs I was looking at.
Clearly somewhere there is a catalogue of my browsing history or something but could someone explain or point me in the right direction to understand the specific process/technology behind it. It's very clever but a bit creepy too!
Cheers
Developed originally by the Russian mafia, for which they were gaoled. Now it is widespread and Google in particular are very active. Basically they use cookies to flag what sites you have been on and then overwrite the normal adverts with ones from sites you have visited. Gppgle then charge the websites for sending you back over there. So JL have to pay Google for the privilege of getting you to say no a second time!
Developed originally by the Russian mafia, for which they were gaoled.
Thanks jjbomber. Can you elaborate more on this statement...what were the Mafia using this method for? I didn't think they advertised for their protection racket 'service' 
I've noticed this before when i've looked at stuff, it's not just john lewis it happens with other websites too, i don't know how it works but i quite like it, it means you get to look at adverts you actually don't mind looking at, it could be worse, it could have been diet pills or something.
I would be interested to know how it works though.
The Rissians were selling the links, the same as Google and Microsoft do. So if the Russiam Mafia re-directed you to JL, then they would get the 50p or whatever it is these days.
The Russians were doing it by planting Spyware on your PC unannounced. This runs in the background and tracks what sites you had visited. Next time you are on the PC and go to, for example, the WhatHiFi site, their adverts would be replaced by the Russian mafia ones. Then you click through to JL and the mafia gets it's 50p. Multiply that by millions of computers worldwide, and it runs into millions of pounds every day.
Nowadays, you will often see sites saying that they are using cookies, which basically does the same job. It stores data on what you did at a particular site. Then the adverts start appearing on your next log on and seem to be forever. So Google and Microsoft are making millions out of it.
As Simon says, at least I'm seeing stuff I might be interested in. Fascinating stuff and thanks for explaining it. Given the number of websites people visit and the amount of web traffic there must be a HUGE number of adverts to choose from to match your previous viewing.
And as a follow up, has this made anyone actually go ahead and purchase something that you'd decided you wouldn't anyway? I can't say that it would for me, but I sort of feel the same about most advertising anyway.