Security Overlays:PFC uses security overlays. An overlay is a frame that rests directly on top of another part of the page. Its purpose is to hide parts of the original page to prevent the user from interacting with it. The user interacts
with the overlay while the overlay interacts with the obscured parts of the original page on behalf of the user. An overlay
provides security features that the original page does not. Since the content in the secure overlay is served from a domain
that differs from the original page, the browser’s same origin security policies prevents the original page from accessing
content in the overlay. PFC overlays Facebook Chat windows with an overlay frame where users read and compose chat
messages while the normal Facebook Chat window only sees encrypted content.