Kolmogorov complexity is a concept in computer science and information theory that measures the complexity of a string of data. It defines the complexity as the length of the shortest possible program (or algorithm) that can produce that string when run on a computer. Essentially, it quantifies how much information is contained in the data by looking at how simply it can be described. This idea was named after the Russian mathematician Andrey Kolmogorov, who contributed significantly to probability theory and algorithmic information theory. Kolmogorov complexity helps in understanding the limits of data compression and the nature of randomness, as simpler strings have lower complexity while more random strings have higher complexity.