Claude Shannon publishes in 1948 'A Mathematical Theory of Communication' (Bell System Technical Journal), establishing the mathematical principles of Information Theory: he quantifies the concept of information (the bit as unit), defines the fundamental limits of representing and reliably transmitting information over a noisy channel, and describes the general architecture of a communication system (source, encoder, channel, decoder, destination). The concept that changes relative to his 1937 thesis (switching algebra applied to logic circuits) is not how to build circuits, but how much information can be reliably transmitted and what the theoretical limit of compression and error correction is — a completely different mathematical framework, later applied to communications, cryptography, and computing for decades (through 1967 per the IEEE plaque).