Hydrogel microspheres (microgels), which consist of crosslinked hydrophilic or amphiphilic polymer chains, are components of stable colloidal dispersions. Their typical size is below similar to 10 mu m, and they exhibit fascinating properties in aqueous solution. Owing to their attractive properties, they have been used for a variety of applications (for example, as templates, sensors, catalysts, and coatings) and have promising prospects for advanced chemical technologies such as drug carriers. In this context, we have been conducting research on microgels, including their synthesis, characterization, assembly, and application. In this focus review, we summarize recent results of microgel research conducted mainly by our group as well as work by our collaborators.