Mites and ticks belonging to class Arachnida, under phylum Arthropoda, are of enormous importance both as foes and friends. These tiny creatures occur in all types of habitats, suitable for living. They are available from the deepest ocean to tops of snow clad mountains, from arctic region to hottest desert. Their food habits are also of diverse nature. Since mites and ticks are our foes being economic pests of agri-horticultural crops, stored products, medicinal plants, spices, some are ectoparasites and endoparasites of vertebrate and invertebrate hosts, causing diseases to their hosts. Some are of great public health importance, being causative agents of various diseases to man. On the contrary, there are many, who are our important friends also, as some are very potential predators, used for biological control. The soil inhabiting form helps in enriching soil fertility. The present book deals with mites of diverse habitats, their importance in agriculture, medical and veterinary sciences. Likewise, ticks of veterinary and medical importance have also been dealt with. Some general account about mites and ticks have also been discussed.