An anonymous reader writes "As expected, Facebook today filed its own patent infringement lawsuit against Yahoo. The social networking giant is claiming the online giant infringes on 10 of its patents. This is a countersuit and will likely lead to some sort of settlement between the two parties. Facebook says Yahoo is infringing on a wide range of its services, including its homepage, content optimization, relevance engine, Flickr photo-sharing service, and advertising throughout the service. Two months ago, Yahoo threatened Facebook with patent war. Last month, the online giant sued the social networking giant over 10 patents and the technology industry made sure to criticize Yahoo like never before."