The second quantum revolution is based on entanglement, discovered by Einstein and Schrödinger in 1935. Its extraordinary character has been experimentally demonstrated by landmark experiments in quantum optics. At Institut d'Optique, we are currently revisiting these landmarks using atoms instead of photons, and after the observation of the atomic HBT and HOM effects, we are progressing towards a test of Bell's inequalities with pairs of momentum entangled atoms.This talk will be an opportunity to know Everything you always wanted to know about HBT, HOM,etc... (but were afraid to ask).