The article provides an overview of one of the most perspective methods of modern precise navigation, namely, the method of inertial navigation. By using the inertial navigation positioning is made of a moving object, which is based on the law of inertia. In this method does not require any external information obtained by optical means, with radio or other means. In its implementation processed parameters of the object measured by the gyroscopes and accelerometers. By integrating these parameters, carried out on-board computer, the coordinates and speed of the object. Difficulty for implementation of inertial systems is the allocation of components accelerometer due to gravity. In this overview, in accordance with the principles that are used in the development and implementation of inertial systems, we consider two types of such devices: "geometric" and "strapdown".