Stratum 1 refers to the first layer of a hierarchical structure, often used in various fields such as geology, sociology, and computer science. In geology, it represents the topmost layer of rock or soil, while in sociology, it can denote the highest social class within a stratified society. In the context of computer networks, Stratum 1 is a level of time servers that directly synchronize with atomic clocks or GPS clocks. These servers provide accurate time to Stratum 2 servers, which then distribute the time to other devices, ensuring precise timekeeping across networks.