Microtubules are essential protein filaments required to organize and rearrange the interior of the cell. They must be stiff with mechanical integrity to support the structure of the cell. Yet, they must also be dynamic to enable rearrangements of the cell during cell division and development. This dynamic nature is inherent to microtubules and comes about through the hydrolysis of chemical energy stored in guanosine triphosphate (GTP). Dynamic instability has been studied with a number of microscopy techniques both in cells and in reconstituted systems. In this article, we review the techniques used to examine microtubule dynamic instability and highlight future avenues and still open questions about this vital and fascinating activity.