This document is meant to provide useful information on the Speex codec but there is absolutely no warranty regarding usefulness or correctness of the information provided. Also, some techniques used in Speex are said to be ``similar'' to techniques used in known codecs. This should not be understood as an acknowledgment that Speex is using any patented algorithm used in these codecs, but merely that comprehension of Speex can be facilitated by thinking that the principles of operation are the same or similar. Of course, there's also the obligatory ``all trademarks are property of their respective owner''.