In this short lecture I want to explain why programmers use 4x4 matrices to apply 3D transformations in computer graphics. We will learn why we need a 4x4 matrix to represent 3D transformations, including the mathematical explanation and also a geometrical intuition. For complete courses on computer science, programming, and mathematics, visit: http://www.Pikuma.com/. Don't forget to subscribe to receive updates and news about new courses and tutorials: https://www.youtube.com/channel/UC8GR0g1deJB_gxWxi_vuxhA Enjoy!