Nuclear reactors are the most intense man-controlled sources of neutrinos. They have played a key role all along the scientific history of neutrinos, first in the experimental discovery of these ghostly particles and then in the determination of their properties, in particular the parameters driving the oscillations during their propagation. par I'll start my presentation by a basic introduction of neutrino physics and the main open questions discussed in the community nowadays. Then I'll discuss the flux of electron anti-neutrinos emitted by the reactor core and the key parameters of their detection. Thanks to the steady progress of the liquid scintillator technology we'll see how the modern experiments entered in the high precision era of reactor neutrino detection with millions of events recorded. In 2011 the last unknown mixing angle, $theta_13$, was measured. This opened the door to future searches for the CP violation phase parameter of the mixing matrix using neutrino beams as well as ultra high precision measurements at reactors to determine the mass hierarchy of neutrinos. Another consequence of this quest of high precision is the revelation of the so-called ``reactor antineutrino anomaly'' that could be explained by the existence of a new neutrino state, a sterile neutrino. I'll present the experimental program in development across the world to test this hypothesis. Finally, routinely detected reactor neutrinos also led scientist to think about the first possible application of neutrinos as a new tool for the surveillance of reactor cores, in the framework of the non-proliferation of atomic weapons. I'll present a brief overview of the various projects and their interplay with improved detection technics for the fundamental research.