computer people: question about privacy on the www

- The IP address of the visitor
- Which page they came from (whether it was another page on my site or some other site. Note that there is no info here if they came from a bookmark or by typing in a URL directly -- the referrer field only shows up when the visitor got there by clicking a link)

From that info, I can tell which pages one user visited in a single sitting, given that their IP address + referrers would make a little path through the pages on my site that they'd looked at. I'd also be able to tell if they reloaded a single page multiple times.

Given the way a lot of internet service providers set up their services, a single user's IP address can change, so it's often hard to track one specific user's multiple visits over time, though in the short term it can be done the way I describe above.

The thing is, log files are a big load of text, and unless you know what you're looking for or have some kind of reporting software that parses them and constructs reports, it's unlikely you'd notice any one user unless they were behaving weirdly. The most common thing I do personally is filter my log file to see where hits are coming from (so I can tell if any other websites are sending me a lot of traffic) and occasionally I will check hits to specific pages if I want to see how they're doing. I rarely if ever track one user's trail through my site.

Can I tell which pages you visit: yes; if I log which pages your IP number went to.

Can I tell if you come back: not really, assuming your IP number is reallocated by your ISP to someone else.

Can I track how you got there: not unless the URL contains something to say where it came from, which would have to be done by design; often search engines do this with their "sponsored links". People often talk about cookies with respect to this; however, you can't read a cookie that was written by a website in a different domain (assuming browser software is working as expected).

Again, assuming no software flaws in your browser, only your browsing habits on a particular site are visible to an individual site.

Furthermore, if an AOL user visits, they may well appear to have a different IP address for each individual page request, making it much harder to track them through the site.

The good news is, however, the sheer volume of freaking data means that we only really pay attention to general trends in traffic. I don't look at this info and go "Wow, look at all this personal information I have about people, mwah hah hah!" rather I go "crap, another report I have to make for the Marketing Department. Feh."

as keith mentioned, cookies are only readable by the site that set them so if ilx has set a cookie on your machine (which it probably has as that's how it rememebers who you are) no other server will be able to read it (so amazon.com can't find out you're an ilx reader for instance).

that said, because lots of ads in commercial websites are served by one or two advertising companies (doubleclick springs to mind, advertising.com is another) then they can tell which other sites that are also served by them you have visited recently and can sell this information to both the websites involved.

have a look through your cookie cache, it's quite enlightening.

i have a bigger problem with sites that require registration and will often lie about my details. giving each one a different (but valid) email address is often useful because it lets you see who sells on your information to spammers.

... etc etc etc...

If I want to move away from gmail and get my own domain and email address, a) is this a valid way to reasonably secure my email? B) can you recommend a registrar ?