1 IntroductionFacial expressions are one of the most important parts within the animation of a 3D character, we are sure that every work done to achieve the character's animation Importantly, all parts together make for good character animation, however, facial expressions reflect a person's emotions. Just by looking at his face, or even just his eyes, you might know how he feels. Body movements can help emphasize the action, but may not be necessary to understand it. This was not an easy task, due to the complexity that characters acquire when interacting with others. Nowadays, computer-made characters are very frequent, not only in animated films; other sections also appear as video games, so making each part as detailed as possible is crucial, as viewers may notice the slight change in the character's face. Facial expression has always been studied by animators, so that they can improve it later on, and the two areas that always take part are physiology and psychology. But depending on the type of animation we are making, the expressions will be different, some will be more realistic and some will be more exaggerated. In this thesis we will examine the different types of animation and how they use facial expression. We will look at cartoonish and realistic character animation as well as common techniques used to achieve the expected result.2 Facial Animation Techniques First of all, to get a good facial expression, we need to shape the character's face and there are two ways to do so, those based on geometric manipulations and those based on image manipulations. Each style has its own... half of paper... articulation is a way of parameterization that will allow you to achieve a more complex expression by articulating the muscles. There are various muscles that need to be taken into consideration when shaping a face. There are the lower facial muscles and the upper facial muscles. As Waters says in his research and as many animators still believe, he divides the face into 5 groups in the lower part of the face which are: upper and lower, those that contract horizontally, the oblique muscles, the orbitals and the laminar muscles. And those that can change the appearance of the expression are located in the upper part of the face and are the eyebrows, forehead and upper and lower eyelids of the eyes. There are three methods to achieve good muscle shaping: spring mesh muscle, vector muscle, and layered elastic mesh muscle.2.3.1 Elastic Mesh Muscle2.3.2 Vector Muscle2.3.3 layered spring mesh muscle