Neutrinos are the most abundant matter particles in the universe and, at the same time, the most difficult to detect. They are so light that they were initially postulated to be massless. However, the discovery of oscillations has shown that neutrinos do have mass, although its value is still unknown. Neutrinos open a window of exploration of the universe since they travel freely through space. In this colloquium I will review the progress in understanding the properties of these intriguing particles and how the next generation of experiments will address the open questions in neutrino physics.