Book excerpt: Boron compounds have been used extensively in organic synthesis for more than sixty years. Some of the best known reactions in synthesis, such as the Suzuki-Miyaura cross-coupling and the hydroboration reaction, involve boron compounds. Several natural products containing boron have been isolated in the last fifty years, including ionophoric macrodiolide antibiotics boromycin, borophycin, aplasmomycins A, B, and C, and tartrolons B, C, and E, as well as autoinducer-2. The study of compounds containing boronic acids for application in pharmaceuticals and materials science has grown tremendously over the last few decades. These include bortezomib, ixazomib, and tavaborole. Several more boron-based drugs are currently in clinical trials. Boron neutron capture therapy has the potential to provide a treatment for various cancers. In addition, materials bearing boronic acids are been studied as potential sensors for biological molecules, such as saccharides and glycoproteins that possess cis-1,2- or cis-1,3-diols.