Book excerpt: Recent progress in the optical detection and spectroscopy of single ions in vacuum confined in electromagnetic traps has led to novel measurements that further our understanding of quantum physics. For example, various workers have achieved direct measurement of quantum jumps, Doppler sidebands, and other fundamental phenomena such as ion crystallization of ions in vacuum trapped by electromagnetic fields. By using laser induced fluorescence and a novel hydrodynamically-focused flow to confine the molecules and reduce the scattering volume, single molecules of the protein B-phycoerythrin with the equivalent of 25 rhodamine 6G chromophores have also been detected. In contrast to the far- field optical approach, recent advances with various near-field spectroscopies such as scanning tunnelling microscopy (STM) have provided images of single molecules of benzene and CO on Rh surfaces and images of liquid crystal molecules on graphite to name a few examples.