Last month, Yahoo set off a bomb when it sued Facebook for alleged patent infringement. Today, Facebook fired back, denying that it violated any patents and claiming that ten of its own were infringed by Yahoo.

Here's what Facebook alleges.

Facebook says a wide variety of Yahoo services infringe its patents, including its Flickr photo sharing system. According to Facebook's countersuit, those servies include:

the Yahoo Home Page, Yahoo's Content Optimization and Relevance Engine ('C.O.R.E.'), [Flickr], and advertisements displayed throughout Yahoo Including on My Yahoo, Yahoo Finance, Yahoo Sports, Yahoo News, Yahoo Games, Yahoo Movies, Yahoo Shopping, Yahoo Travel, Yahoo Autos, and Flickr. [...] According to Yahoo, advertisements contributed 80 percent of Yahoo's revenue in 2011, accounting for more than $4 billion.... Yahoo claims a 300 percent increase in click-throughs on the Yahoo Home Page since launching its C.O.R.E. system, which it says "personalizes 2.2 billion pieces of content for Yahoo Users" every day and is used across all of its services. Yahoo claims that Flickr has over 51 million registered users and over 80 million monthly unique visitors worldwide. Yahoo claims that Yahoo News and Yahoo Sports are the most popular news and sports sites in the United States.

The ten patents that Facebook claims were infringed -- and for which it is demanding an injunction against Yahoo -- are as follows:

U.S. Patent No. 7,827,208 (The "208 patent"), known as "Generating a Feed of Stories Personalized for Members of a Social Network," which was issued on November 2, 2010, and which Facebook claims was infringed by Flickr's Photostream, Recent Activity, and Group Activity features.

Exhibit A - US7827208





Patent No. 7,945,653 (The "653 patent"), known as "Tagging Digital Media," issued on May 17, 2011, and which Facebook alleges was infringed by Flickr's People in Photos feature.

Exhibit B - US7945653





Patent No. 6,288,717 (The "717 patent"), known as "Headline Posting Algorithm," which was issued on September 11, 2001, and which Facebook argues was infringed by Yahoo's home page and any other Yahoo home pages that utilize C.O.R.E. to identify items for display.

Exhibit C - US6288717





Patent No. 6,216,133 (The "133 patent"), known as "Method for Enabling a User to Fetch a Specific Information Item from a Set of Information Items and a System for Carrying Out Such a Method," which was issued on April 10, 2001, and which Facebook says Yahoo infringed with ads displayed across all Yahoo sites.

Exhibit D - US6216133





Patent No. 6,411,949 (The "949 patent"), known as "Customizing Database Information for Presentation with Media Selections," which was issued on June 25, 2002, and which Faceook says is infringed by ads displayed across all Yahoo sites.

Exhibit E - US6411949





Patent No. 6,236,978 (The "978 patent"), known as "System and Method for Dynamic Profiling of Users in One-to-One Applications," which was issued on May 22, 2001, and which it says was infringed by ads displayed across all Yahoo sites.

Exhibit F - US6236978





Patent No. 7,603,331 (The "331 patent"), known as System and Method for Dynamic Profiling of Users in One-to-One Applications and for Validating User Rules," which was issued on October 12, 2009, and which it claims Yahoo infringed by displaying ads across all its sites.

Exhibit G - US7603331





Patent No. 8,103,611 (The "611 patent"), known as "Architectures, Systems, Apparatus, Methods, and Computer-Readable Medium for Providing Recommendations to Users and Applications Using Multidimensional Data," which was issued on January 24, 2012, and which it argues Yahoo infringed with ads displayed across all its sites.

Patent No. 8,005,896 (The "896 patent"), known as "System for Controlled Distribution of User Profiles Over a Network," which was issued on August 23, 2011, and which it says Yahoo infringed with "the ability to establish relationships with other users and set privacy settings on the Yahoo Flickr photo sharing service."

Exhibit I - US8005896





Patent No. 8,150,913 (The "913 patent"), known as "System for Controlled Distribution of User Profiles Over a Network," which was issued on April 3, 2012, and which Facebook says Yahoo infringed with "the ability to establish relationships with other users and set privacy settings on" Flickr.