Opera Software has added a filter to its web browser software that blocks phishing sites, following the example set by rivals Microsoft and Mozilla.
PhishTank, overseen by open-source group OpenDNS, is a collaborative clearing house that allows anyone to submit and track data about phishing sites. GeoTrust provides digital certificates.
Phishing is a form of online fraud whereby criminals use forged websites that often look like sites of banks or other trusted financial institutions to trick users into giving up personal information. Filters such as the one in Opera 9.1 alert users when they may be visiting a known phishing site so they can proceed with caution and choose not to provide requested information to that site.
Microsoft's Internet Explorer 7 (IE 7) and Mozilla's Firefox 2.0 browsers also include filters that block phishing sites.