The study of microorganisms which are present in the soil is referred to as soil microbiology. It focuses on the functions of microorganisms as well as the effect which they have on the properties of soil. Such microorganisms are classified into diverse categories such as bacteria, algae, fungi, protozoa and actinomycetes. Each group has specific characteristics and functions in the soil. These microbes make the soil rich in nutrients and minerals and produce hormones that encourage growth. They also help in stimulating the immune system of plants. Healthy soil increases fertility in various ways. It supplies nutrients such as nitrogen and protects against pests and diseases. This book aims to shed light on some of the unexplored aspects of modern soil microbiology. Some of the diverse topics covered herein address the varied branches that fall under this category. This textbook will serve as a valuable source of reference for those interested in this field.