Zk-SNARK, which stands for zero-knowledge succinct non-interactive argument or knowledge, is the most popular zero-knowledge protocol.
This a space of increasing importance, as zero knowledge systems are an area of active development that stand to disrupt how authentication works. While the math is intense, the overall ideas are not hard to understand.
What is zero knowledge?
Zero knowledge is the attempt to use the smallest amount of information possible when verifying a statement. It works to devise proofs that avoid transfer of extra data.
Ground zero for this field is the paper Knowledge Complexity of Interactive Proof Systems, which appeared in a few editions during the 1980’s. As the name implies, the paper undertakes to get an understanding of how knowledge behaves in proving statements between interacting systems.