This chapter focuses on metafeatures, which forms the core of our method for temporal classification. It begins with an example of the application of the techniques that will be implemented in TClass. TClass is discussed in greater depth in Chapter 5. This first taste of TClass is intended to give the ``big picture'' and to show how metafeatures are employed to accomplish temporal classification. The inspiration behind metafeatures is then outlined, followed by a formal definition of metafeatures. Practical details of metafeature implementation are discussed, and finally two cute refinements of metafeatures are given.