All three authors are specialists in interaction design and human–computer interaction(HCI). In addition they bring skills from other disciplines. Yvonne Rogers is a cognitive scientist, Helen Sharp is a software engineer, and Jenny Preece works in information systems. Their complementary knowledge and skills enable them to cover the breadth of concepts in interaction design and HCI to produce an interdisciplinary text and website.. They have collaborated closely, supporting and commenting upon each other's work to produce a high degree of integration of ideas with one voice. They have shared everything from initial concepts, through writing, design and production.