Crystal growth is a surface process. So, understanding the growth of a crystal requires close examination of its surface. On a mesoscopic scale we image surface morphologies by advanced optical microscopy, scanning electron microscopy and atomic force microscopy. In this way step patterns, adsorption layers and epitaxial nanocrystal structures are studied, which we further interpret by using analytical models for crystal growth. On an atomic scale the solid-liquid interfaces are examined by surface X-ray diffraction (using synchrotron radiation from the ESRF, Grenoble). In this way the atomic structure of the surface of, for instance, KDP (KH2PO4) and NaCl crystals in contact with aqueous solution and liquid monolayers of metals on semiconductor or metal surfaces under ultrahigh vacuum conditions is determined. Besides the surface structure, this method also provides information on the ordering properties of the liquid adjacent to the crystal surface.