Since the turn of the millenium, Working Groups of the W3C have been concentrating on the development of XML based security standards, which are paraphrased as XML Security. XML Security consists of three recommendations: XML (Digital) Signature, XML Encryption and XML Key Management Specification (XKMS), all of them published by the W3C. By means of a review of the available literature the authors draw several conclusions about the status quo of XML Security. Furthermore the current state and focuses of research as well as the existing challenges are derived. Trends to different application areas - e.g. use of XML Security for Mobile Computing - are also outlined. Based on this information the analyzed results are discussed and a future outlook is predicted.