title: what is the chat box of face-book known as
body: <p>i am working on asp.net </p>
  
  <p>i want to make a chat room which should be attach like facebook </p>
  
  <p>can any tell me do's and dont's </p>
  
  <p>wht is it called 
  how can i start ?
  designing  part ?</p>