It is one of the Crafting professions called Enchanting. Here is brief overview:
Enchanting provides Glyphs in Elder Scrolls Online. Glyphs are enchantments which are applied on gear. Theres three types of glyphs: armor glyphs, weapon glyphs, and jewelry glyphs . Glyphs are crafted at enchanting station, typically found in towns. The combination of runes used to craft the glyph affects the quality and effects of the final glyph, much like the combination of reagents does in Alchemy.
To craft glyphs, the enchanter needs Runes. These are gathered in the world. The runestone nodes visually appear to be very small-sized shrines, which come in different colors. The color of the shrine defines the type of the rune.
When an enchanter crafts new glyphs, they will learn the translation of the runes used in the process. The translations define what kind of effects the rune will have in a glyph.
http://tamrieljournal.com/crafting-and-professions/enchanting/
Personally, this crafting skill line is the most challenging/hardest that I have done. But it is worth it because of the ability to enhance gear to give it that extra stats that are important.