Alan Becker, most famous for "Animator vs. Animation", a viral video from 2006. Here is his tutorials of 12 Principles of Animation in depth. He teaches animation using Adobe Flash/Animate, and some Photoshop and Minecraft stuff.

12 Principles of Animation

1. Squash & Stretch 

2. Anticipation

3. Staging

4. Straight Ahead & Pose to Pose

5. Follow Through & Overlapping Action

6. Slow In & Slow Out

7. Arcs

8. Secondary Action

9. Timing

10. Exaggeration

11. Solid Drawing 

12. Appeal 

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Checkout another article on principles of animation: http://animationsupplement.com/index.php/resources/474-thinking-to-learn-animation-understand-the-12-principles-of-animation