It enables the password that you have typed to be temporarily displayed on the screen
Here is a "Password Reveal Button" for your browser, it always appears on the right-hand side of password boxes on web pages.
User can just click and hold down the left button via mouse. It will display the password instead of symbol "stars".
It's a easy way to let user check the password typing.
My Blog: http://studiobinghuan.blogspot.tw/?view=flipcard