The Shannon–Hartley theorem is a cornerstone of information theory that defines the maximum rate at which information can be reliably transmitted over a communications channel. It specifically addresses channels subject to Gaussian noise, providing a mathematical bound on how much error-free data can be sent given a specific bandwidth and signal power.
Named after Claude Shannon and Ralph Hartley, the theorem applies the principles of the noisy-channel coding theorem to analog communication links. By establishing the concept of channel capacity, it allows engineers to determine the theoretical limits of data transmission efficiency in the presence of interference.