Anti-phishing software consists of computer programs that attempt to identify phishing content contained in websites, e-mail, or other forms used to accessing data (usually from the internet) and block the content, usually with a warning to the user (and often an option to view the content regardless). It is often integrated with web browsers and email clients as a toolbar that displays the real domain name for the website the viewer is visiting, in an attempt to prevent fraudulent websites from masquerading as other legitimate websites.