Plasma physics is a growing field in aerospace engineering. This book is a brief introduction to the scientific and technological applications, pitched as a course text for students. The book is divided into two parts; the first section covers molecular collisions and the more relevant plasma elementary processes of ions and electrons at the atomic and molecular level. The second part introduces the physical description of plasmas as a system of interacting particles. Throughout the book, basic concepts are introduced in a simple way and mathematical developments and demonstrations are examined thoroughly, with updated experimental data sets provided. Each chapter concludes with references and commentaries for further insight in the essential points. Two important applications of plasma physics in aerospace technology are introduced in the last chapters. The electric propulsion in space and low-pressure microwave electric discharges, currently denominated multipactor and corona. The book is for master and undergraduate courses in aerospace engineering and physics. It is also aimed at both non-specialists and professionals involved in laboratory testing for space qualification.