This book gives an overview of the research field of artificial cilia, a novel technology for controlling and sensing fluid flow at microscopic scales. This field is inspired by nature, namely by naturally occurring cilia which are tiny hairs covering biological cells and that are used already for over a billion years by nature to generate and sense fluid flow. The research field started less than a decade ago and has grown fast in recent years, since it offers very interesting options for flow control in lab-on-a-chip devices.