Structure and dynamics of disks in galaxies

One the most cited papers in astronomy is Ken Freeman's 1970 paper on exponential disks in galaxies. In this contribution I review what has been done in this area since then and what we can infer about systematic properties of disks in galaxies from surface photometry, HI synthesis observations and measurements of stellar kinematics. Most disks have radial truncations at $3.6 \pm 0.6$ radial scalelengths $h\subr{R}$. Galaxy disk thicknesses $h\subr{R}/h\subr{z}= 7.3 \pm 2.2$ imply that these disk cannot be ``maximum disks''. I briefly discuss a recent study of the ``superthin'' edge-on galaxy IC 5249.