Many of the websites (e.g. Online Banking websites) have a secure area which is only accessible to the user after he provides correct Username/Password. Some of them have case-sensitive passwords.
If a user is not aware (while entering the password) whether his CAPS lock key is ON then his login will fail as the password is case-sensitive.
This is one of the features in Windows based applications that was lacking in Web based application. You all might have noticed it while logging in Windows XP/Windows Server 2003, that a “Speak-out” bubble is displayed with a message that “CAPS Lock is On” while entering the password if the CAPS lock is On.
This feature was highly desired in Web Applications until today when i came across a nice article at 4GuysFromRolla about an ASP.NET control which provides the exact functionality.
Scott Mitchell has explained the working of this control in detail in this article.
Here is the link to the article: [ Warning the User when Caps Lock is On ]