RCM is based on the standard confocal microscope as it was developed in the early 1980s (Brakenho et  al. 1979). e improved axial resolution (=optical sectioning) is the most important property of confocal microscopy and is oen the reason why biomedical researchers decide to use this technique. However, most researchers do not realize and do not understand under which conditions the confocal microscope has improved lateral resolution (Mc Cutchen 1967, Sheppard and Wilson 1978, Cox et al. 1982, Cox and Sheppard 2003). erefore, we will here resume the basics of improved axial and lateral resolution in confocal microscopy compared to wideeld.