Personalizing a web application by Creating User Controls in .NET
Personalization helps the users to store their preference in later use it when they log in to the web application. Personalization is tied to the identity of the user.
The user interface of the web page is customized according to the users preference that is already stored. Personalizing a web application means that the look and feel should be the same whenever the user uses that application.
Personalization and Web parts go hand in hand. Usually web parts are used in web pages to personalize the page. if you are using web parts ASP.Net stores the personalization data in the application services database which is found in the folder app_data.
By using the web.config file you can also create a separate database file for personalization data. By default an SQL Server Express database file is used. The Personalizable attribute is added to the custom control that is created to control personalization. Since a User Control is also used as web part control, the personalization also applies to the user control.