How does a textbox works?

hi,

there are somany event with Textbox control.
even if it also depend are you use winform application web application or else?

normally KeyDown, TextChanged, KeyPress, KeyUp is fired when you change data on text box.
Please refer below link for know more about it.

http://msdn.microsoft.com/en-us/library/system.windows.forms.textbox_events.aspx

for webapplication
http://msdn.microsoft.com/en-us/library/d0chd93e.aspx

hope this will help you.