This lecture introduces the concept of kinematics, which focuses on the motion and deformation of bodies independently of external forces. Starting with the basic problem of a deforming body, the instructor explains the reference and deformed configurations, establishing a fixed coordinate system. The lecture covers topics such as deformation gradient, inverse deformation, and stretch ratios. It also delves into the relationship between deformation and relative motion of material points, as well as the description of length changes and angle variations. The discussion extends to the concept of Lagrangian strain tensor and its application in defining strain based on initial material points. The lecture concludes with a detailed explanation of large deformations and the transition to the deformed configuration.