In the publishing industry we use words with which you may, at some point, come in contact. If you are interested only in ePublishing you really won't need to be concerned with them. But if you are hoping to publish a print copy of your work, it might be a good idea to become familiar with some of the printing jargon.
The trimmed sheets of paper that a reader turns in a printed (and bound) book are called leaves. Each leaf has a front and a back; a page is one side of the leaf. One side of the leaf lies in the right hand position when the book is opened, and the other side lies to the left when the leaf is turned. When the book is open, the right side is called recto, and the left side is called verso.
The whole page numbering system is based on recto and verso; rectos are always odd-numbered, and versos are always even-numbered. Did you ever wonder why the first page of a book is on the right hand side? It's page 1; that's an odd-numbered page, and rectos are always odd-numbered. Now you know!
And speaking of page numbering, the printing term is pagination. Page numbers are actually called folios and are most commonly found at the top of the page. If they are printed at the bottom, they are called drop folios. Page numbers that do not appear--such as on the first page of a chapter--are referred to as blind folios. Sometimes pages are inserted into printed books after the pagination is already finished (e.g., color illustrations, photo galleries printed on a different kind of paper). These are NOT blind folios but are called non-paginated folios.
The position of the folios are most commonly found at the top of the page on the far right on rectos and are referred to as flush right recto and at the top of the page on the far left on versos and are referred to as flush left verso. Drop folios usually appear centered on each page; however, you will also occasionally find them flush right recto or flush left verso.
So when your editor contacts you with questions about where you prefer your folios to appear, you can WOW him/her by answering either flush right recto and flush left verso, or you can WOW him/her even further by discussing drop folios. Most publishers won't expect you to know these terms, so it might give you a few extra points when communicating with your publishing company. And that never hurts.