An overview of the current state of cone-beam tomography using `exact' analytic methods is presented. The fundamental theories of Smith and Grangeat are described as the even and odd parts of generalized unifying formulation. Various versions of the orbit condition for data sufficiency are reviewed, with examples to illustrate the relative restrictiveness and applicability to situations with truncated projection data. Existing strategies for reconstruction algorithms, and methods of handling redundant data are summarized. Finally a brief discussion of `equivalent methods' is included, with a demonstration that Tuy's inversion formula is equivalent to Grangeat's method.