Heart sells Daedra member of the College of Winterhold Enter, owner of the alchemy shop in Whiterun Arcadia (only after you complete the quest by delivering frost salts), sometimes hearts get caught in the sale of other alchemists if the level of alchemy you have more than 25.
This ingredient is not necessary to get on the battlefield, especially if you prefer to develop skills such as trade or eloquence, not combat magic and weapons possession. After defeating the Daedra they can be picked up heart. The quest "Azura's Star" you can find three hearts Daedra: during the passage of the character finds a unique stone shower, gets inside it and grapple with three strong fire benders, which turn out to be demonic entities. After completing the tasks in this location every ten days updated facilities, including new demons, so you can occasionally visit this place again to produce four heart. All four of the demons, so for once you can get four hearts. Where to get Daedra heart? Walking in Skyrim quest "Pieces of past glory", during which you need to collect the shards of Mehrunes Razor, the character falls at the Shrine of Mehrunes Dagon, where he will have to encounter a few Daedra and kill them. To create such armor in the smithy and the legendary the Forge Atronach. You will also need ebony ingots and leather strips. On each item is a sword, shield, helmet, armor, gloves – you need one heart. Daedra heart can be used not only in alchemy, but blacksmithing for making Daedric armor and weapons.
If the character eats a Daedra heart in its raw form, not in the composition of potions, then at high alchemy skill it is possible to obtain a magical effect or even more.