Strategies Bug Bytes Warnings Ladder Rankings Technical Help Sanct. They are small, socketable objects, like Gems, but are much more complicated in function. It's unknown if the markings mean anything in any language, or if they are just whatever the Blizzard artists made up. All 33 runes look different, so in theory you could memorize them and not need to hover on one to know what it was. They also have a weird squishy sound when dropped or placed in Inventory, as though they were organic items, rather than the rocks they look like.
Runes have some very nice properties when socketed.
A wide variety of properties, and all 33 of them do different things in different item types. We have every rune listed with their properties on the Runes Stats page, in the top left navigation table. The real power of Runes comes in the Rune Words. These are special combinations of Runes that create Unique-like items with enormous bonuses. Making a Rune Word is tricky though.