A basic overview of the essential aspects of the very rich boron chemistry is discussed to give elements for the comprehension of the structural behavior and chemical properties of boron-containing molecules. Some introductory elements are given on the peculiar chemical properties shown by boron, which derive from its electronic configuration; bonding orbitals and electronegativity are fundamental to understand boron behavior. The structural complexity deriving from these properties, which results in a variety of structures of elemental boron and boron derivatives, is subsequently introduced, followed by an outline of the main classes of boron-containing compounds. This overview begins with inorganic boron derivatives, followed by carbon-containing compounds, and, finally, organic boron compounds are also considered.