English: Comparison of aerogel fabrication strategies showing typical transitions into an aerogel. (a) shows the supercritical drying process where precursor materials undergo gelation prior to supercritical drying. Often, these processes include a solvent exchange step after gelation to provide better fluids for supercritical drying. (b) shows a standard freeze-drying technique where an aqueous solution is frozen and the ice crystal formation dictates the alignment of the precursor materials and thus, the resulting pore structure of the dried aerogel.