ANC stands for "active noise cancellation," which is a feature that is increasingly common in headphones and earbuds. ANC headphones have tiny microphones built-in to pick up sound from the surrounding environment, and the ANC technology then inverts these soundwaves, and a speaker located inside the earphone cancels them with neutralizing, "anti-noise" soundwaves. There are different ways to which Active Noise Cancellation can be applied, and the three most common implementations are feedforward ANC, feedback ANC, and hybrid ANC. ANC headphones are particularly useful for commutes and long-distance travelers, as they can cancel out consistent sounds like plane engines and the trundling of trains. However, one potential downside to ANC is the reduction in situational awareness, and it may be harder to tell when someone is trying to speak to you.