This article gives a complex overview of the topic of eyeball movements which can be described as the commonest potentially intentional human behaviour. The observations of intentional human behaviour have been carried out by scholars for centuries, yet nowadays due to the technological development it is possible to introduce far more accurate and advanced eye-tracking devices. The paper describes thoroughly the perception process, differentiates types of eye movements, then moves on to the mechanisms that ensure the stability of perception and comments on modern methods of measurement of eyeball movement. The article underlines that eye-trackers have already been applied to various areas of life and science, such as linguistics, psychology and law, just to name a few. The current studies in the field of eye-tracking concentrate mostly on the cognitive processes behind the eye movement. Eye-tracking research has been experiencing a growing interest, yet the topic demands even more attention and exploration as a vast and fertile branch of knowledge.