Prologue Personas, imaginary people that model and present the essential user segments, are a popular tool in user-centred design. They are formed on the basis of studies and observations of users, for aiding designers and guiding the creation of features, interaction, UI navigation, and terminology in products. In this book we use personas for illustrating the concepts, trends, and technologies which are discussed. Throughout the text, we present brief moments in the personas’ lives and experiences related to per- sonal content. The moments highlight the terms and concepts pre- sented in the text. Let us introduce these personas: ANGIE, 16, STUDENT Angie is a student at the local Belleville High, near London. She lives in a nice house with her parents and her younger brother Adam, 14. Her uncle Ron is also close, but physically far away living in Nevada. They keep in touch by e-mail and occasional video chat sessions. Angie has little money to spend, but still enjoys an unusu- ally good selection of electronics, as her dad receives good staff discounts at Dixons. Her otherwise girly room is stocked with a laptop, music players, a video camera, a digicam, and a mobile phone or two. She has a relatively active social life, often hanging out in cafés with the girls. Her boyfriend Eddie goes to the same school. They often IM in the wee hours, sometimes seeing over video. She records all the sessions, to Eddie’s dismay. Angie keeps a private diary, posts pictures on the Net, IMs, e-mails, and text messages with her friends. She downloads music occasionally, but gets most of her MP3s from her boy- friend, who is into P2P fi le sharing.