This chapter covers the complex chemistry and diverse mechanisms of acaricides that are important in managing the ticks and mites. Ticks and mites are ectoparasites that adversely affect the animal and human health. The chapter also provides an overview of the advantages and disadvantages of different acaricides. It also provides a comprehensive classification of acaricides, categorizing them into mineral source acaricides, organochlorine acaricides, pyrethroid, carbamates, natural sulfur insecticides, amidine acaricides, organotin acaricide, organic phosphorus acaricide, heterocyclic acaricide, microbial acaricide, and botanical acaricides. This classification system aims to facilitate the understanding and selection of acaricides, enabling the development of effective integrated pest management strategies against ticks and mites. It then explores their modes of action, highlighting how they disrupt essential physiological processes in mites and ticks. Key mechanisms include the inhibition of acetylcholinesterase, modulation of sodium channels, and interference with mitochondrial function. Through a detailed understanding of acaricide chemistry and modes of action, this chapter provides valuable insights for the development of novel acaricides and the sustainable management of acaricide resistance, aiming to enhance both crop protection and animal health.