Winkler, who has dyslexia, wrote the best selling children's book series, Here's Hank, which follows the adventures and struggles of a dyslexic kid named Hank Zipzer.
Dyslexia is a common learning difficulty that can cause problems with reading, writing and spelling.
It's a specific learning difficulty, which means it causes problems with certain abilities used for learning, such as reading and writing.
Unlike a learning disability, intelligence isn't affected.