Biological processes that replicate, preserve and use the genetic information encoded in DNA must operate in the context of chromatin, a highly organized complex of DNA and proteins. These proteins do not merely package the DNA in the tiny volume of the nucleus, but impart the structure the ability to change according to the requirements of the specific process the DNA is involved in. Moreover, chromatin structure is used by the cell to control the activity of DNA. In this volume the basics of chromatin structure and dynamics are presented by established experts in the field.