How to create different headers and footers on odd and even pages

Sometimes odd and even pages need to have different headers and footers. In a document with facing pages (mirror margins), odd-numbered pages appear on the right side and even-numbered pages on the left. You may want left-aligned headers on even-numbered pages and right-aligned headers on odd-numbered pages; this way, the headers always appear on the outside edges of your document. You can even create different odd and even headers and footers for each section in your document.