In this section of the blog, I will go into depth on what each animation principle is and why they are a significant part of the animation process. Although the terms have been updated through their initial creation dates, the principles importance and definitions remain the same. Created initially for hand drawn animation, they apply to digital animation just as effectively. The more principles used in a scene will provide a more entertaining and realistic piece of animation. Every student and professional animator should have a strong understanding of these twelve principles.
Squash and stretch is considered the most important principle and discovery in animation. This theory promotes the concept that characters or beings made of flesh will depict movement within its initial state while in motion. Study your own face while exaggerating a chewing motion to witness a great example of squash and stretch. Being flattened out or bunched up are the two examples of squash, while the only example of stretch is any form of extension. Squash and stretch helped animators evolve past rubber hose animation. Characters that changed shapes were now able to keep their same volume. By exaggerating the squash and stretch, animators created stronger character poses. Beginning animation artist usually practice animating a bouncing ball to understand this principle. The ball is supposed to stretch closer to both sides of its impact, where it would squash or flatten. The more bounces the ball takes the less exaggerated the squash and stretch will become over time. Squash and stretch also implies what material the object being animated is. The less squash and stretch in an object the more the audience depicts that object to being rigid.
Anticipation is the principle that allows viewers to realize the sequence of action happening in an animated scene. It allows us to prepare the audience for an action that has yet to happen. Anticipations can be anything as small as a facial expression and as big as full body movement. A great example of this is how humans jump. We don’t automatically go up in the air, but instead we crouch down first and then push up. The act of crouching down before the jump is the anticipation. The lack of anticipation creates a mechanical feeling in an animation. Animators can use anticipation as a joke if what follows the anticipation is not what is expected. Walt Disney made it a priority to fix unpredictable animation by making each action clearer for the audience. By use of anticipation the animator can guide the audience’s eye to what is important on screen. The greater the anticipation is the more powerful the succeeding action will become. Timing is important to create a realistic relationship from the anticipation and the main action. A way to see if your animation is missing anticipation is to play your frames backwards. If the action looks to rigid, the anticipation is most likely not there.
Having roots from theater, staging has become the most universal principle of animation. Staging is the act of making any idea totally and unquestionably clear. This principle allows animators to communicate exactly what an audience is seeing. Staging must be used in every aspect of the story. If you are staging an environment you want to add assets that will complement the mood you are trying to accomplish. To create a romantic mood we would add flowers, candles, a star filled night sky, etc. You can also stage an action by choosing the correct camera frame. By doing a close up to a characters face we can draw emphasis to the frown, smile, or look of concern. It is recommended however to stage one action at a time, allowing viewers to absorb exactly what is seen one at a time. Using the rule of thirds can help stage your camera frame. Implied lines can also help guide the audience’s eyes to what they should be looking at on screen. The use of screen direction also helps viewers maintain a consistent narrative throughout a scene. Staging actions helped animators realize the importance of constructing actions in silhouette. This meant that if the silhouette was legible the action would be easily understood.
The next animation principle, straight ahead action and pose to pose, are the two ways to describe how to approach animation. Straight ahead action begins without a solid plan, only the beginning and end of the story is known. This free-form style of animation starts at one pose and explores new directions at the whim of the animator. In a professional setting, pose to pose is more favorable. It allows animators to quickly layout the action throughout each shot. Animators can then pass off their “key” poses, to an in-between animator. Pose to pose is better in terms of clarity, which as stated before is extremely important in animation. Combining straight ahead action and pose to pose brings out the best in both ways of animation approach. It is hard to achieve straight ahead action when there is a need for consistency in perspective. Pose to pose also allows for more control when it comes to staging the action in the scene. It is often used alongside reference video by animating the key poses we are now able to time our animations properly.
Follow through and overlapping action is the principle that everything in an action occurs at different times. This means when character comes to a stop, one thing stops first, and another thing stops last. Characters without follow through and overlapping action would translate as stiff to an audience. There are five sub sections to this animation principle. The first is that if a character has any appendages, these will come to a stop last. Second, the body does not stop all at once, some parts lead while the others play catch up. Third, flesh will move slower than bones. This “drag” creates a life like performance in characters. Fourth, is that the follow through can be a description of your characters personality. What your character does after an action is indicative of their nature. Lastly, is the “moving hold,” some technique animators used to allow viewers to acknowledge the attitude of a pose.  To have a pose remain lifelike, the characters still had to maintain movement within that pose. This was done by having a normal pose followed by an over exaggerated one. Follow through and overlapping action is not exclusive to the parts of the characters body, but can also include an props or objects utilized by that character.
Slow in and slow out, also known as ease in and out, kept the focus on the character poses, by having more frames next to each extreme pose. Easing in starts at the beginning of an action and easing out finishes one. This principle is tied to timing and staging but is used mostly when follow through and overlapping action are not. By studying realistic body mechanics, such as the slow in and slow out, animators can take liberties while keeping a solid base to the action or movements in a scene. This principle is tied to physics terms such as position, translation, velocity and acceleration. Full understanding of this can help animators realize what their limitations are.
Arcs are the natural paths living things take while performing an action. It is extremely rare for living organisms to move in a mechanical way or outside of an arc like path. Arcs remove stiff or rigid motion in animation. This principle allowed animators to plot out their movements and helped create a path for the follow through action. Because the points plotted out for a path can be interpreted in many ways, it is important for key frame animators to communicate with in-between animators on how the arc in an animation should be completed. Having movement that is done outside of an arc can ruin the life of any action.  
Secondary action is an action that enhances or solidifies the primary action. This principle also adds another dimension to an action by creating a complimentary feeling through action. An example of this would be the actions of a child throwing a tantrum. The primary action might be the child falling to the floor, while the secondary action could include pounding of fists, kicking, and crying. If for whatever reason the secondary action conflicts with the primary, it translates as being staged incorrectly. Imagine that same child now laughing instead of crying, it would completely change the idea that was initially sought out. Each secondary action should be staged so that the audience is able to absorb it. A wrong placement of secondary action could make the principle obsolete in any scene. By solidifying the main action first and then adding a second pass of action, animators can keep each action looking natural. Secondary action can reveal additional personality traits of the character being animated.
Timing is the relationship to the spacing and number of frames it takes to complete an action. The more space there are in between to frames the faster the action will be. Slower action will have more frames per action spaced relatively close together.  Two extreme poses can have different meaning depending on the number of in-between frames and their spacing. The more complex an action is the more frames are likely needed to complete that action. Experimentation with timing and spacing is the only way animators build an expertise on the subject.
Exaggeration is the act of making an idea stronger by taking it one step further. Exaggeration can be a distortion of physical attributes, but it is not limited to that. Animators can also exaggerate character traits, feelings, or personalities. If a character is tired, make them more tired and if they are slow, make them slower. Exaggeration helps hammer down an idea that an animator is trying to get across. Making an action too extreme is almost impossible in animation. Exaggeration can be utilized in other animation processes such as squash and stretch, staging, arcs, secondary action, timing, solid drawing and appeal
Solid drawing helps illustrate the action of a character through their pose or silhouette. These poses were meant to have three-dimensions which included weight, depth and balance. One thing to avoid while posing is referred as “twins”, this is the act of having two separate body parts do the exact same things as one another. Characters will look more natural if each part of their body is posed differently and doing something unique. Another way to tell how successful a pose is, is to put that pose in a silhouette. If the action is still recognizable through this process, the audience will have a greater understanding to the idea of the animator.
Appeal is important for animated characters, without this audience members might not enjoy looking at our animations. It is just as important to have an appealing villain than an appealing hero character. Audiences will absorb more of what their characters are doing if they like the way they look. A movement can also lack appeal if it is too jerky or difficult to apprehend. It is often beneficial to stay away from overly detailed characters or action to allow for audience comprehension. The phrase “less is more” often applies to this principle. Close ups in animation have been a problem for appeal, since it tended to flatten characters, but it has improved over time with three-dimensional technology and software. Appeal is even more important today since audiences are watching animated works on more than one medium and in a variety of different platforms.

Utilizing these twelve principles will help anyone create solid works of animation. These principles also apply to other forms of animation including but not exclusive to motion graphics, design and UX design. Straying away from these principles can provide gags or be used to achieve a certain idea. It is important to remember that a strong understanding of physics will also help an animator utilize the principles properly.