Wikipedia
OpenDNS is a company and service which extends the Domain Name System (DNS) by adding features such as phishing protection and optional content filtering to traditional recursive DNS services.
The company hosts a cloud computing security product suite, Umbrella, designed to protect enterprise customers from malware, botnets, phishing, and targeted online attacks. The OpenDNS Global Network processes an estimated 60 billion DNS queries daily from 50 million active users connected to the service through 24 data centers worldwide.
Previously OpenDNS provided an ad-supported service "showing relevant ads when we [show] search results" and a paid advertisement-free service. The services are based on closed source.
On August 27, 2015, Cisco acquired OpenDNS for in an all-cash transaction, plus retention based incentives for OpenDNS. Cisco said that it intended to continue development of OpenDNS with its other cloud-based security products, and that it would continue its existing services.