How does Alexa know your traffic stats?

This seems strange to me

[androidtech]

How does Alexa know what your traffic statistics are, even if it's an approximation?

Where do the get their data?

Especially their related sites data.

The only thing I can think of is that all their data is based on web surfers that have their toolbar plugged into IE, but that's a small percent of the internet. Wouldn't their traffic stats be horribly wrong if that were the case?

thanks.

[martinibuster]

The only thing I can think of is that all their data is based on web surfers that have their toolbar plugged into IE...

Correct.

A large percentage of users are in Korea so you may see a disproportionate share of Asian sites as the top visited sites. It's also been testified by WW members in the past that installing the toolbar and visiting your own site will raise the stats to a level that may not match your log files. Alexa once tried to market it's stats like Nielsen and Comscore but that business didn't go anywhere.

Many people swear by it, many people think it's an unreliable source of data. Pick a side that you feel comfortable with.