The NIST stands for National Institute of Standard and Technology. It was an agency established in 1901 and it is a non regulatory federal agency within the US department of commerce. Many services and products rely on the technology, measurement and standards provided by the NIST.
I rely heavily on the service provided by the NIST because most of the products and services I use pass through NIST. From the smart electric power grid that supply electricity to my home and office to the computer system I used for my work, all are provided standard for by NIST.