No-one knows exactly where the ankh came from, but we do know that the concept of life associated with the ankh encompassed life-sustaining waters, air, food and life-force. Many libation jars and vessels were made in the shape of the ankh, as it was thought the power of the ankh would bless the water within and make it more powerful. You can pour water or wine through the loop of an ankh as a form of blessing.
The ankh is also known as the key of life. The word for mirror was the same as that for ankh, suggesting the need to look truly at oneself and not fall prey to delusion.