The contents of a web page is arbitrary, but controlled by the entity owning the domain named displayed in the address bar. If HTTPS is used, then encryption is used to secure against attackers with access to the network from changing the page contents. For normal password usage on the WWW, when the user is confronted by a dialog asking for his password, the user is supposed to look at the address bar to determine whether the domain name in the address bar is the correct place to send the password.[1] For example, for Google's single sign-on system (used on e.g. youtube.com), the user should always check that the address bar says "https://accounts.google.com" before inputting his password.