ASP.NET web parts - not stored in a cookie

Recently I was reading the MCTS ASP.NET 3.5 exam preparation book. I finished the lesson about web parts. The author said that user personalization is stored in a database and tracked by a cookie in a web browser.

I checked开发者_开发问答 the database - it's there.

It seems however that the personalization information has noting to do with a cookie. It is recognized across multiple browsers. I even tried deleting all cookies and the webparts state are the same across browsers.

Do you have any idea WHY is that and HOW does it work without a cookie?

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This may shed some light on how, Web Parts Personalization Overview, you basically setup SQLServer as the provider to manage the personalization data