12. Appeal

Appeal in a cartoon character corresponds to what would be called charisma in an actor.A character who is appealing is not necessarily sympathetic — villains or monsters can also be appealing — the important thing is that the viewer feels the character is real and interesting.There are several tricks for making a character connect better with the audience, for likable characters a symmetrical or particularly baby-like face tends to be effective.

11. Solid Drawing

The principle of solid — or good — drawing, really means that the same principles apply to an animator as to an academic artist.The drawer has to understand the basics of anatomy, composition, weight, balance, light and shadow etc.

computer animators in theory do not need to draw at all, yet their work can still benefit greatly from a basic understanding of these principles.

10. Exaggeration

Exaggeration is an effect especially useful for animation, as perfect imitation of reality can look static and dull in cartoons.The level of exaggeration depends on whether one seeks realism or comedy.The classical definition of exaggeration, employed by Disney, was to remain true to reality, just presenting it in a wilder, more extreme form.

9. Timing

Timing in reality refers to two different concepts: physical timing and theatrical timing.It is essential both to the physical realism, as well as to the storytelling of the animation, that the timing is right. On a purely physical level, correct timing makes objects appear to abide to the laws of physics; for instance, an object's weight decides how it reacts to an impetus, like a push.Theatrical timing is of a less technical nature, and is developed mostly through experience.It can be pure comic timing, or it can be used to convey deep emotions. It can also be a device to communicate aspects of a character's personality.

8. Secondary Action

Adding secondary actions to the main action gives a scene more life, and can help to support the main action. A person walking can simultaneously swing his arms or keep them in his pockets, he can speak or whistle, or he can express emotions through facial expressions.The important thing about secondary actions is that they emphasize, rather than take attention away from the main action. If the latter is the case, those actions are better left out.In the case of facial expressions, during a dramatic movement these will often go unnoticed. In these cases it is better to include them at the beginning and the end of the movement, rather than during.

7. Arcs

Most human and animal actions occur along an arched trajectory , and animation should reproduce these movements for greater realism. This can apply to a limb moving by rotating a joint, or a thrown object moving along a parabolic trajectory. The exception is mechanical movement, which typically moves in straight lines.

In computer animation fk mostly give you an automatic arc While in ik you have to manually add keys to make it move in arc this because ik just calculates the shortest distance from point a to b and covers it.

6. Slow In and Slow Out

The movement of the human body, and most other objects, needs time to accelerate and slow down. For this reason, an animation looks more realistic if it has more frames near the beginning and end of a movement, and fewer in the middle.This principle goes for characters moving between two extreme poses, such as sitting down and standing up, but also for inanimate, moving objects and bouncing ball.

Bouncing ball and pendulum might be the best eg for explaining this principle.When the ball is going up its got more energy so its going up with speed but soon it starts losing its energy and it starts to slow down because earth's gravity is pulling it down finally it loses all its energy starts to fall slowly then starts to increase its speed downwards till it hit the ground again.

5. Follow Through and Overlapping Action

These closely related techniques help render movement more realistic, and give the impression that characters follow the laws of physics. "Follow through" means that separate parts of a body will continue moving after the character has stopped. "Overlapping action" is when a character changes direction, and parts of the body continue in the direction he was previously going. A third technique is "drag", where a character starts to move and parts of him take a few frames to catch up.Exaggerated use of the technique can produce a comical effect, while more realistic animation must time the actions exactly, to produce a convincing result.

Check out this eg some one gave me this test in order to understand this principle.

4. Straight Ahead Action and Pose to Pose

"Straight ahead action" means drawing out a scene frame by frame from beginning to end, while "pose to pose" involves starting with drawing a few, key frames, and then filling in the intervals later.By drawings we mean making a pose here(for people who are not familiar with 2D animation)

"Straight ahead action" creates a more fluid, dynamic illusion of movement, and is better for producing realistic action sequences. On the other hand, it is hard to maintain proportions, and to create exact, convincing poses along the way. "Pose to pose" works better for dramatic or emotional scenes, where composition and relation to the surroundings are of greater importance.

Computer animation removes the problems of proportion related to "straight ahead action" drawing; however, "pose to pose" is still used for computer animation, because of the advantages it brings in composition.

Me personally feel more comfortable with pose to pose that just a personal choice that doesn't mean its better than other its just that me end up making crap with straight ahead method :p.

3. Staging

This principle is akin to staging as it is known in theater and film. Its purpose is to direct the audience's attention, and make it clear what is of greatest importance in a scene; what is happening, and what is about to happen, whether that idea is an action, a personality, an expression or a mood.This can be done by various means, such as the placement of a character in the frame, the use of light and shadow, and the angle and position of the camera.The essence of this principle is keeping focus on what is relevant, and avoiding unnecessary detail.

For eg. a lot of time you might have seen that when a important character enters a scene the camera moves from his feet upward to his face that tells us how important that character is we want to show a impact with him.So by making him take maximum amount of screen presence we let the audience have their focus on him.

2. Anticipation

Anticipation is used to prepare the audience for an action, and to make the action appear more realistic. A dancer jumping off the floor has to bend his knees first; a golfer making a swing has to swing the club back first. The technique can also be used for less physical actions, such as a character looking off-screen to anticipate someone's arrival, or attention focusing on an object that a character is about to pick up.

Lets say a character is getting ready to punch he anticipates look fig 1. The audience becomes ready that some thing is going to happen or else the scene will come and go and the audience will be ooh what just happen because they were not ready for it.Then he punches fig 2 or may be he falls down(cartoon style :D) either way people are ready for it.