The Technical CCD Systems (TCCDS) consist of thermo-electrically cooled CCD detector heads together with the electronic hardware and software for the control of the CCD and readout of the data. Two different types of CCD heads equipped with a small and a large format CCD chip are used. The small format CCD systems will be used primarily for auto-guiding and field acquisition at the main foci of the VLT. The large format CCD systems are intended mainly for wavefront sensing applications. An overview of the primary modes of operation of the TCCDS and the corresponding fields and exposure conditions for these modes is given in Table 1. The term “Technical CCD Systems” is derived from the intended application in the VLT because due to the excellent CCD head parameters and the system performance a scientific application will be offered too.