I write in cookbooks. If i change the recipe or add something or leave out something. I will also make notes on quilt patterns if I change anything. Some patterns call for strip piecing but if I want to make it scrappy, I have to do the math and figure out how many of each piece to cut. I will write that down for future reference. They are my books. My grandma also wrote notes in her cookbooks and patterns and now that I have them, its a treasure to me to see her handwriting and know what she was thinking when she did this.