There are many types of bio-signals with various control application prospects. In this book possible application domain of electroencephalographic signal was regarded. The implementation of EEG signals, as a source of information used for control of external devices, became recently a growing concern in the scientific world. Application of electroencephalographic signals in Brain-Computer Interfaces (BCI) (variant of Human-Computer Interfaces (HCI)) as an implement, which enables direct and fast communication between the human brain and an external device, has become recently very popular. Also some information regarding using various types of EEG equipment in order to apply the most appropriate one was presented in this work together with some experiments conducted for that purpose.