Non-interactive zero-knowledge proof

Non-interactive zero-knowledge proof (also known as NIZK or ZK proof) is a way for someone to prove that they know something without actually having to tell what they know. For example, if you know the answer to a math problem, you can use a NIZK proof to show that you know the answer without giving away what the answer is. It can also be used to prove that someone has a certain piece of information (such as a password) without actually revealing what the information is. Basically, a NIZK proof allows you to prove something without revealing the details.