When transferring files from one computer to another, it sometimes changes the page layout of the book. The most common problem is called text re-flow. Re-flow is the sliding or shifting of text and pictures from the page that you had them on to a different page. Different font settings for various printers are usually the cause of this shifting, but there are other software reasons also. Sometimes the typist may insert several hard returns to finish a page and move to the next chapter instead of using a hard page break at the bottom of the page. Hard page breaks are inserted by positioning the cursor at the bottom of the page and pressing the Ctrl and Enter keys together. It is highly recommended that this be done when you reach the end of a chapter or want some extra white space at the bottom of a page. Hard page returns are not necessary when submitting a PDF file because PDFs won’t re-flow.