A Linear Block Code is a method used in coding theory to encode data for reliable transmission over noisy channels. It works by taking a fixed-size block of data and adding extra bits, known as redundancy, to create a larger block. This helps in detecting and correcting errors that may occur during transmission, ensuring that the original data can be accurately retrieved. The key feature of a linear block code is that it operates on linear combinations of the input data. This means that if you add two valid codewords together, the result is also a valid codeword. This property simplifies the process of error detection and correction, making linear block codes widely used in digital communication systems.