WebPart properties are just like ASP.NET control properties, they are used to interact with and specify attributes that should be applied to a WebPart by a user. Some of the attributes you see with ASP.NET 2.0 properties are WebDescription, WebDisplayName, Category, Personalizable, and WebBrowsable. Although most of these properties come from the System.Web.UI.WebControls.WebParts class, ones like Category come out of System.ComponentModel namespace.