The paper is paying attention to the basic anatomical and morphological characteristics of insects. Insects can be differentiated by external characteristics as well as internal. According to the anatomical characteristics the body of insects is divided into three main parts: the head , chest and abdomen. Further they can be differentiated by other organs that are placed on individual parts of the body. On the head of insects they can be differentiated by mouthparts, eyes and antennae. On the chest they can be differentiated according to whether they have wings, and according to the shape and size of the wings if they are a good flyers. According to the type and the number of legs we can differentiate them whether they are ground beetles or jumpers. We can differentiate them by position of abdomen, and we have three types: sitting , stalk and hanging abdomen which is characteristic of wasps, bees and bumblebees. Insects have an open circulatory system, but with different colors of blood. Nervous system is ladder alike, and digestive system is differentiated by the type of diet.