Lecturer: Manuel Mazzara Abstract: --------- With Web 2.0 social media are becoming the major sources for reading news and for quick communication. However, most of what can be found on the Internet has no substantial value or reliability. How quality information and untrustworthy gossip can then be differentiated? Polidoxa is a social platform with embedded trust-based search functionalities. Usage logs represents a clear trace of persons' preferences in terms of people, information sources, topics etc. By using these data, it is possible to determine how users trust each other. Trust metrics are then used to rank the information searched within the platform. We expect that this ranking will help users find information posted by like-minded people.