3.14.2 Greatest hits from previous weeks

3.14.2.1 What are the most common pitfalls awaiting new users?

http://mathematica.stackexchange.com/questions/18393/what-are-the-most-common-pitfalls-awaiting-new-users

 
As you may already know, Mathematica is a wonderful piece of software. 
However, it has a few characteristics that tend to confuse new (and sometimes not-so-new) users. That can be clearly seen from  ...
 

- asked by Dr. belisarius (341 votes), answered by Michael E2 (197 votes)

3.14.2.2 How to make this beautiful animation

http://mathematica.stackexchange.com/questions/112700/how-to-make-this-beautiful-animation

 
How to make an animation of following gif in Mathematica? 
 
 
 
Edit: The animation shown above was created by Charlie Deck in processing. 
 
And how to make 3D analog? 
 
I tried first few steps 
 
line =  ...
 

- asked by vito (47 votes), answered by C. E. (50 votes)