Much has been made of "big data", our ability to gain novel insights from a comprehensive set of data points, but a lot of it is hype, and marketing-speak to sell more tools and consulting. In this talk, I will explain what Big Data really is, why it isn¹t just a marketing fad or the tool du jour, but a new way of making sense of the world around us, and consequently why Big Data matters a great deal, in particular also in the context of semantic technologies. But I will also mention why we need to be cautious and well aware of Big Data limitations when utilizing it.