I discuss one of the two main kinds of representations, namely, symbolic or digital representations (words are typical examples of symbolic representations) that contrast with icons, pictures, or images that are examples of analog or iconic representations. My aim is to explain symbolic representations and discuss their main properties. Bringing to the fore the main properties of symbols will help us understand the profound changes in hominin brain structure and mentality required for symbolic representations to emerge and, mainly through, language shape our brain and behavior. The discussion concerning the main properties of symbols and symbolic systems, namely, their discrete and non-dense character, the fact that symbols refer through conventions, and the fact that symbols compose discursively by means of a set of established rules, is important for the aims of this book because these properties are necessary for understanding the cognitive capacities required to enable cognizers to have such representations. One, then, may turn to examining when in the evolution of our species and for which reasons these capacities first appeared. If symbols emerged from a background of indices and icons, to explain the cognitive novelty of symbolic cognition one should compare the properties of symbols with those of icons and pinpoint those differences between these two representational forms that require that novel cognitive capacities develop in order for symbolic thought to become possible.