Cacography means writing things in a confusing or messy way that makes it hard to understand. Imagine trying to read a book but the words are all jumbled up and written in weird letters that you don't recognize. That would make it very hard to understand what the book is about! Cacography can happen for lots of reasons - maybe the person writing is in a hurry, or they don't know how to spell the words they are trying to write, or they are just not paying attention to what they are doing. Whatever the reason, cacography can make it hard for people to communicate with each other, which is why it's important to practice good handwriting and spelling when writing anything down.