Freeze-casting, the templating of porous structures by the solidification of a solvent, have seen a great deal of efforts during the last few years. Of particular interest are the unique structure and properties exhibited by porous freeze-casted ceramics, which opened new opportunities in the field of cellular ceramics. The objective of this review is to provide a first understanding of the process as of today, with particular attention being paid on the underlying principles of the structure formation mechanisms and the influence of processing parameters on the structure. This analysis highlights the current limits of both the understanding and the control of the process. A few perspectives are given, with regards of the current achievements, interests and identified issues.