The first release of the Warlords of Draenor patch notes revealed that certain glyphs will be learned automatically during the leveling process. These glyphs, as stated by developer Celeston, are chosen largely based on their usefulness during the leveling process. They will also serve as a reminder that you even have the ability to use another glyph -- often, leveling characters aren't aware when they're able to use a glyph, or what a glyph is at all.
Currently, as mentioned in the patch notes, glyphs are usually acquired on the auction house. Since every player needs these glyphs, the glyph market is a cutthroat place where a player leveling fresh can run themselves broke even if they only buy the ones they need. This change isn't one that's friendly to scribes making a killing on the auction house, but it certainly is friendly to new characters. Keep in mind that not all glyphs will be learned automatically -- only the leveling essentials. You can refer to the patch notes to see which ones will be learned and when or follow along below.