Facebook just returned fire on Yahoo in their emerging patent battle by filing its own patent infringement assertions — claiming that Yahoo is infringing ten patents. Yahoo took the initial shot in this skirmish last month with a patent infringement complaint alleging that the social media giant infringed ten of its patents related to page advertising, online privacy, and interaction between network members.

Just days after Yahoo initiated the litigation, we learned that Facebook had purchased 750 patents from IBM in an apparent attempt to bolster its lacking portfolio of under 60 issued US patents. However, it doesn't appear that any of those IBM patents made their way into Facebook's countersuit today. So, let's take a look at what Facebook actually is using to target Yahoo.

US Patent No. 7,827,208 - this patent claims priority back to 2008 (granted 2010) and covers a method of generating a personalized story on a social network based on the user's actions and the common actions of other users. Facebook claims that Photostream, Recent Activity and Groups Activity features on Flickr infringe the patent.

US Patent No. 7,945,653 - this patent, identifying Mark Zuckerberg as the first listed inventor, claims priority back to 2008 (granted 2011) and covers a method of allowing a user to reject his or her identification in digital media posted by another user. Facebook claims that the People in Photos feature of Flickr infringes the patent.

US Patent No. 6,288,717 - this patent claims priority back to 1999 (granted 2001) and was just assigned over to Facebook three days ago. It covers a method of providing a user with selected, ranked and posted topics of interest on their page based on that user's identified interests. Facebook claims that Yahoo's home page infringes the patent.

US Patent No. 6,216,133 - this patent claims priority back to 1995 (granted 2001) and was originally filed by Philips Corp. The patent was assigned to Facebook in December 2011. The broadest claims cover a method of fetching information based on a user's past interaction patterns. Facebook alleges that My Yahoo, Yahoo Finance, Yahoo Sports, Yahoo Travel, Flickr, and various other Yahoo services infringe the patent.

US Patent No. 6,411,949 - this patent claims priority back to 1999 (granted 2002) and was also originally filed by Philips and assigned to Facebook last December. The patent covers a system for "enhancing content" by selecting and supplying media to a user based on the user's profile or preferences. Like the '133 patent, Facebook alleges that numerous Yahoo services infringe this patent.

US Patent No. 6,236,978 - this patent claims priority back to 1997 (granted 2001). The patent covers the creation of a user profile based on static factual information (e.g., sex, age, location, etc.) for the user and dynamic information based on transactions by the user (e.g., purchase preferences). Again, Facebook claims Flickr, Yahoo Finance, Yahoo Sports and other services infringe.

US Patent No. 7,603,331 - this patent claims priority back to 1997 (granted 2009) and covers a method of providing a user with dynamic recommendations based on historical data for the user. Flickr and the litany of other Yahoo services are listed again as infringing.

US Patent No. 8,103,611 - this patent claims priority back to 1995 (granted 2012) and covers providing a user with a recommendation based on "multidimensional data," using the Cartesian product of the dimensions. This is a nerdy one, and continues the trend of alleging that nearly all of Yahoo's services infringe.

US Patent No. 8,005,896 - this patent claims priority back to 1998 (granted 2011) and was assigned over to Facebook in February. The patent covers the specific network procedures for allowing users to request and exchange content. Facebook alleges that Flickr infringes this patent.

US Patent No. 8,150,913 - this patent claims priority back to 1998 (granted 2012) and was also just assigned over to Facebook in February. The patent covers controlling access to user profile information on a network, and allowing users to individually grant other users access to interact with videos and photos.

That's the rundown. No big surprises here. The vast majority of the patents cover what you would expect in social media patents: control over user interaction and the content and information users display and access on the network. It is worth noting, however, that only the first two patents on the list actually derive from work done at Facebook — the rest were recently assigned or licensed to Facebook from others. Yahoo will be required to file its response to these infringement allegations later this month, barring a time extension, so we'll keep an eye on things and keep you updated.