Acari is a subclass of arachnids that includes mites and ticks. These small creatures can be found in various environments, from soil and water to plants and animals. They play essential roles in ecosystems, such as decomposing organic matter and serving as food for other animals. Acari are characterized by their eight legs and lack of antennae. They have a simple body structure, typically divided into two main parts: the cephalothorax and the abdomen. Some species are beneficial, while others can be pests or transmitters of diseases to humans and animals, highlighting their diverse impact on health and agriculture.