This book reviews the current state of information on reactive oxygen and nitrogen species and their role in cell communication during plant growth, development and adaptation to stress conditions. It addresses current research advances made in the area of reactive oxygen and nitrogen species (ROS and RNS) signaling. These free radical molecules are important in plant-microbe interactions, responses to abiotic stress, stomatal regulation and a range of developmental processes. Due to their short half-life, high diffusion capability and ability to react with different components in the cell, ROS and RNS participate in various processes connected with signaling and communication in plants. The book's respective chapters address the latest advances made in the niche area of ROS and RNS in plants. It offers a valuable guide for researchers and students alike, providing insights into cutting-edge free radical research. The information on specialized topics presented is also highly relevant for applied fields such as food security, agricultural practices and medicinal use of plants.