Animating on Ones, Twos, and Threes.
Ones, twos, and threes refer to how long a single image holds on camera in relationship to frames per second. Ones mean every single frame is different, so at 24 frames per second you'll have 24 individual and unique drawings with that second.

• Animating on Twos makes it feel like being handmade
  => Apply "Posterize Time" effect on the object (e.g. text) in After Effects and change the Frame Rate property (12 for Twos)

Limited Animation
a process in animation that doesn't redraw entire frames but reuses common parts btw frames (e.g. background)

Ví dụ: Bouncing balls

It only takes 3 frames (doesn't have to) and, say 20% squashing and stretching

Ví du: A character lifting a weight
A falling ball (the speed should keep increasing until it hits the ground)

SPACING
The distance btw poses
Uneven spacing: it has inconsistent distance btw each frame
Ví dụ: Một quả bóng rơi xuống thì mỗi frame quả bóng sẽ đi được 1 khoảng xa hơn.

STOP MOTION TIP:
Halving or doubling the distance btw each pose is a great way to achieve Ease

Anticipation (antic) is an action that precedes and prepares for the main action

Ví dụ: throwing, kicking a ball, swinging a bat or golf club ; jumping

Cause: Kinetic Energy: energy which a body possesses by virtue of being motion
In other words, by the virtue of something moving, it has built up energy, and it takes time for that to settle to a stop or even start to create the energy.
Because of different objects, mass, or friction and other variables, they can take longer/ shorter time to start / stop.

Ví dụ:

• If your character is running across the scene, their arms and legs may be moving at a different rate from their head. This is overlapping action. Likewise, when they stop running, their hair will likely continue to move for a few frames before coming to rest – this is follow through. These are important principles to understand if you want your animation to flow realistically.
• For example Follow through refers to the way parts of the body continue to move after the body is stopped. Overlapping action describes the offset between the timing of the main body and its other parts (ví dụ tay và chân)
  
  
  

• Một người dừng di chuyển nhưng khuyên tai của họ vẫn di chuyển

Understand Disney's 12 principles of animation

12 Principles of Animation (Official Full Series)

Secondary Action: Adding texture to a character's performance
OR Gestures that support the main action to add more dimension to the character animation.

Ví dụ:

• For example a character may be walking angrily. The primary action is the legs and the secondary action is everything else: the arms swinging, the head bobbing and the facial movements.
• A character is about to knock on a door. The secondary action of the other hand will communicate what kind of door knocking this is.
  
  • If it's a fist, it makes him look angry.
  • If it's dainty, it gives them a graceful, happy vibe.
  • If it's tucked close while the head looks back and forth before knocking, it communicates that he doesn't want to be discovered.
• A character is standing up (primary) and shaking his head to show that he is very angry (secondary)

Things, for e.g. limbs, often move in arcs, not straight lines
Ví dụ: đầu quay, tay chân quay

It can be the diffence btw our Planning and Final products (needs polising)
=> You can track movements of a point, for example the wrist

Timing: This principle states that the personality and nature of an animation is greatly affected by the number of frames inserted between each main action.

SPACING: The distance (spatial) btw each pose that is between each frame

To maintain volume