What are Pixar's famous storytelling rules that Hollywood can't stop copying?

The answer

In 2011, Pixar story artist Emma Coats tweeted a list of 22 storytelling principles she had learned while working at the studio. The tweets went viral, collecting over 10 million views when compiled into a single article, and were syndicated by Buzzfeed, Mashable, and Entertainment Weekly. Key rules include: 'You admire a character for trying more than for their successes,' 'Coincidences to get characters into trouble are great; coincidences to get them out of it are cheating,' and the structural formula 'Once upon a time ___, every day ___, until one day ___, because of that ___, until finally ___.' Coats later said she wished she had called them 'guidelines' rather than 'rules.' The list became a standard reference in film schools, writing workshops, and Hollywood development offices worldwide.