What is an interface? Can interfaces be ‘transparent’? What are the relationships between different interfaces? Do they form a network? Can we apply an ecological model to interface evolution? What are the roles of users and designers in the ecology of interfaces? Interfaces have multiplied, and it is possible to find them not only in the analogical objects (the interface of a TV remote) and digital devices (a videogame interface) that surround us, but also as company-client interfaces. We should not be surprised if one day we find pedagogues talking about 'the teacher–student interface’. Any communicative interchange belongs to the interface universe. We could spend a lifetime talking about interfaces. And yet, while we strive to design, use, reflect, define, classify and write about them, interfaces continue to reproduce, contaminate and live a seemingly autonomous existence, far away from our theoretical ruminations.