Exploring the fundamental properties of neutrinos has been one of the most challenging and inspirational field in physics and it links many areas of particle physics, nuclear physics, and astrophysics. Neutrinos gave us the first evidence of physics beyond the Standard Model: neutrinos are massive and mixed. We now measure the three-flavor mixing matrix to an amazing precision, especially given how weakly interacting neutrinos are. However, key fundamental questions such as the nature of neutrinos, absolute neutrino mass scale, neutrino mass hierarchy, and total number of flavors are still unanswered. The nature of neutrinos, i.e, whether neutrinos are their own anti-particles and how the neutrino mass is generated, is arguably the most critical questions in the field and can be probed with neutrinoless double-beta decay. Internationally, there are many experiments competing to push the half-life sensitivities to double-beta decay by another few orders of magnitude to discover or rule out the Majorana neutrinos in the inverted neutrino mass hierarchy region. I will give a brief review of the results and status of the active experimental programs. Special focus will be on the CUORE (Cryogenic Underground Observatory for Rare Events) experiment, which will search for the neutrinoless double beta decay of Te-130 using a bolometric technique.