How does a website or advertisement know where I am?
When visiting some websites you may notice that the page or ad on that page is marketing directly to you. For example, it may be advertising a local business in your city or state. This advertising is known as geo-targeting. It uses an algorithm which analyzes your Hostname and IP address to determine your location.
This information gathered often points to the location of your ISP. However, with more sophisticated systems it may be able to also gather your city.
Using the above methods geo-tracking can also be done when registering on a website. For example, after registering the site may store a cookie on your computer and use that cookie to give you more targeted advertising.
How much information can geo-targeting get on me?
The rudimentary form of geo-targeting that obtains its data from your hostname or IP address will not be able to get anything more than your City, State, Country, and sometimes Zip code. More personal information such as your full home address, phone number, name, birth date, age, sex, etc. cannot be obtained from your computer without you filling out a form first.
Where can I see a web page that shows information about me?
See our system information script for an example of the type of information a website can get about your computer.