When we type password while logging onto Unix, it is not visible on screen. How is this achieved?

I want to make an application in Unix which accepts password, but it is not visible on screen, just the way it happens when we log onto a Unix terminal. Thanks :)

When we type password while logging onto Unix, it is not visible on screen. How is this achieved?
The stty -echo command is used to turn off the display while entering. after use use stty echo to turn it back on. In a gui, any standard password text box should do this automatically.