Biological diversity or biodiversity refers to the diversity, or variety, of plants and animals and other living things on earth. There are many levels of diversity-from DNA and genes to species, populations, ecosystems, and communities. This diversity is the beauty of nature and is essential for the survival of human beings. Life on Earth would not exist if its rich biodiversity were severely altered. Species and the ecosystems in which they live are linked together though the flows of energy and materials. A change in the life of one species could ripple throughout an ecosystem, changing the life of many other species, including humans. But due to the greed of mankind, there has been a great threat to the biodiversity. Many human activities, which stem from the population explosion, have threatened biodiversity. Pollution, over hunting, global climate change, habitat fragmentation and degradation and introduction of exotic species are some main causes of loss of biological diversity. Thus it is necessary to think about the problem of biodiversity loss and to come out with some solution for its conservation. This book is a humble effort in this direction. The main objective behind this book is to make people aware about biological diversity and to sensitize them about the urgent need for its conservation. The book is divided into two sections: Section I includes review articles by various academicians and the Section II has research papers by various scientists and academicians. We hope these review and research articles would be able to motivate the students, academicians and general public about various issues of biological diversity and its conservation.