XKeyscore is a surveillance program that was used by the National Security Agency (NSA). The program was first revealed by Edward Snowden, a former NSA contractor, in 2013.
According to documents leaked by Snowden, XKeyscore was a system that allowed the NSA to search through vast amounts of internet traffic and other data in order to identify potential threats and targets for surveillance. The program was able to collect and analyze data from a variety of sources, including email, chat messages, websites visited, and social media activity.
XKeyscore was reportedly used to target individuals for surveillance and to collect intelligence on a wide range of topics, including terrorism, cyber threats, and foreign intelligence. The program was controversial because it allowed the NSA to collect and analyze large amounts of data on individuals without a warrant or probable cause, and because it raised concerns about the privacy of internet users.
It is not clear if XKeyscore is still in use or what, if any, modifications have been made to the program since it was first disclosed.