The diseases that are caused by the hypersensitivity of the immune system towards organisms or elements present in the environment are known as allergies or allergic diseases. These diseases can cause severe to mild damage in different people based on their immune system. Most common allergies found in humans are food allergies, allergic asthma, hay fever, anaphylaxis, atopic dermatitis, etc. The objective of this book is to give a general view of the different aspects of allergic diseases. It is a valuable compilation of topics, ranging from the basic to the most complex researches in the field of allergic diseases. It will prove to be immensely beneficial to students and researchers in this field.