Book excerpt: This book describes the state of the art in the field of bioanalytical nano- and microsystems with optical functionality. In 12 chapters distinguished scientists and leaders in their respective fields show how various optical technologies have been miniaturized and integrated over the last few decades in order to be combined with nano- and microsystems for applications in the life sciences. The main detection and characterization technologies are introduced, and examples of the superiority of these integrated approaches compared to traditional ones are provided. Examples from e.g. the fields of optical waveguides, integrated interferometers, surface plasmon resonance or Raman spectroscopy are introduced and discussed, and it is shown how these approaches have led to novel functionalities and thereby novel applications.