History sniffing is the art of tracking where people have been on the internet. Essentially, it is to help advertisers target very specific advertisements to very specific people. However, it seems that it happens most obviously with porn sites which kinds of makes the the whole idea of 'history sniffing' sound a little dirty. Yet, the biggest problem is that this kind of snooping is really tantamount to an invasion of privacy. It is an invasion of privacy because you, the internet surfer, has not consented to your data being collected in this manner nor have you consented for it to be collected for this purpose.
Nevertheless, it would be unfair to label this as exclusively a porn site thing. It is clearly not. The data being harvested can be done through a visit to a news site, while you are doing your internet banking, or if you are visiting a porn site for the purposes of research. Some of the biggest 'offenders' based on the research / survey data was Morningstar.com and Newsmax.com. Morningstar is a financial services website and Newsmax is a news website. For example, a recent survey, conducted by the University of California at San Diego, found that most internet search browsers allow for history sniffing to continue unabated.
However, the report based on this survey also found that the more recent versions of Google Chrome prevented history sniffing from occurring. Also Apple's latest versions of Safari do not allow history sniffing to take place. Microsoft's Internet Explorer does not yet prevent history sniffing from happening although the next version will, yet will come at a price as it will seemingly disable other useful features such as allowing your computer to recognise where you have been previously. The other popular browser that continues to allow history sniffing is Mozilla Corp's Firefox.
I am currently using the latest version of Google Chrome, so with a bit of luck I am not currently susceptible to history sniffing.
It is worth noting that one's passwords are not at risk here. This technology is not being used to harvest passwords or any other personal data except for where you have been. It really is about following your trail and then modifying advertising to give you, the "consumer", the most personalised service possible.
It is also worth noting that it might not matter too much longer with respect to what internet browsers in conjunction with advertisers want as US regulators are looking at requiring the use of a "Do Not Track" tool that is designed for no other reason than to stop advertisers from tracking specific individuals in order to target them with equally specific internet bargains.
I am no techno wizard so I am never sure whether this data even know it is stated that it is being used only for advertising purposes cannot be worked to develop a comprehensive profile of one's habits. Perhaps it is better to err on the side of caution if doing things that may be misconstrued if they were to ever become publicly available.