One of the most important open questions in modern physics is the riddle of the nature of Dark Matter. Observations, e.g. galactic rotation curves, show that about a quarter of the mass in the universe is in form of Dark Matter. These, up to now only indirect, observations are the main motivation for direct Dark Matter search experiments as CRESST-II, which aim to identify the nature of Dark Matter. CRESST-II is searching directly for Dark Matter in the form of hypothetical WIMPs. Within the framework of this work the functional principles of the CRESST-II detector modules are analyzed and discussed. Therefor the parameters have been identified which determine their sensitivity and the understanding of their behavior has been developed in detail.