textbox change event while typing

i have a small search info  system ..i,e one textbox and below it i have one button ..if i write something in textbox and click button then i bind data in a gridview as per the text written in textbox so the requirement is if iam writing something in textbox, gridview below should start binding data related to what iam writing(without clicking any button)..can we do this in ?  i tried to with the textbox changed event but nothing is happening when im typing or when im removing focus from textbox