It is now almost 20 years since the journal Fluctuation and Noise Letters (FNL) was first published hence this book is to commemorate this important milestone. This book consists of 55 reprinted articles from the first 20 years of FNL, together with a short Introduction explaining their context and significance. In selecting the papers, the Editors had taken into account not only citation counts, but guided also by the perceived interest and scientific importance of the work. All selected articles are arranged across eight themes.