Hard-to-read writing can refer to a variety of different types of writing, such as CIPHER, SCRAWL, and CODE. CIPHER is a type of writing that uses symbols or numbers to represent letters, making it difficult to read without the key. SCRAWL is a type of writing that is written quickly and sloppily, making it hard to read. CODE is a type of writing that uses a set of symbols or words to represent a message, making it difficult to decipher without the key. All three types of writing are difficult to read without the necessary knowledge or key.