Abstract Mössbauer spectroscopy offers information about the structural, electronic, and dynamic properties of Mössbauer-active isotopes. Within this contribution we will limit ourselves to 57Fe Mössbauer spectroscopy and discuss how electronic and structural information of iron centers in inorganic and bioinorganic compounds as well as iron proteins can be obtained. An introduction to the basic principles and necessary sample requirements is followed by examples of Mössbauer spectroscopic work on metallic iron, iron nanoparticles, and thin films. The main part of this contribution contains an overview of selected examples of iron compounds in almost all oxidation states known so far, ranging from zero-valent iron carbonyls to very recently reported ultra-high-valent Fe(VI) coordination compounds. In addition, a short overview on the theoretical calculation of Mössbauer parameters like isomer shift and quadrupole splitting by means of density functional theory is given. These calculations have been improved considerably in recent years and are expected to be used by an increasing number of inorganic chemists for the interpretation of spectroscopic results.