The joy of purling backwards really shines when it comes to stranded knitting, ESPECIALLY when you have to trap floats. For a photo tutorial click here - https://www.moderndailyknitting.com/community/ask-patty-purling-backwards/
To learn more about knitting and purling backwards, check out the class: https://pattylyons.com/product/improve-your-knitting/
To take a 1 hour technique taster class on purling backwards: https://education.pattylyons.com/courses/technique-taster-purling-backwards