Autocomplete is a function in most modern browsers (IE 7+, Firefox, Chrome, Safari, and Opera) that remembers commonly named entries in previous forms and enters it on new forms.
This can be a handy tool for users so they don’t have to keep entering common information. However, for a developer, it can be an extremely annoying and potentially dangerous feature.
Take for example a form with a credit card field. If a user accesses an e-commerce store on a public computer like at a library or school, the autocomplete feature can store that information of previous users.
The good news is that you can turn this feature off on forms by simply adding an addition tag to input or form fields.
You can turn off the autocomplete by simply adding autocomplete=”off”.
<INPUT NAME="name" SIZE=40 AUTOCOMPLETE="off">
In addition, you can also use it for the full form, however it’s also recommended that you add it to the individual input fields as well
<FORM AUTOCOMPLETE = "off">
Since this is not an “official” html value, it will break W3C validation, however for the sake of security it’s worth this exception.