A setting that specifies the password field as required, recommended, or optional, and includes a message for prompting users to enter a recommended or required value
Note:
The capture of information and the display of characters in the field is for visual purposes only. No attempt is made to hide the value of the field from the programming interfaces or when submitting data. If you want to secure your information, you must use a secure link (such as SSL) to encrypt the data as it is transmitted.
See also 

About password fields in interactive forms