Humans are natural-born communicators, using a rich semiotic toolkit spanning multiple communicative modalities, including speech, writing, sign, and gesture. Iconicity — the resemblance between form and meaning — is one important part of this toolkit. Examples of iconic communication include iconic gestures, such as pinching the fingers together to depict a small object, and onomatopoeias, such as using the English words “bang” and “beep” to imitate sounds. Traditionally, iconicity has been marginalized to the fringes of language, said to be the exception, rather than the rule. To this day, linguists and cognitive scientists are taught that language is instead ruled by the “principle of arbitrariness”, the idea that there is no direct relationship between form and meaning. In this talk, I will argue that this widely cited principle has it the wrong way around. Arbitrariness is actually not a design feature of language…. but iconicity is! To make my case, I will give an overview of exciting new experimental, corpus, and typological research that demonstrates how languages make much more use of iconicity than traditionally assumed, and how iconicity performs crucial functions in language acquisition and language evolution. Taken together, this research points to an ongoing iconicity revolution that is sweeping through linguistics and the cognitive sciences, fundamentally transforming the way we think about language.