The Hara is the center of the etheric or chi body. It is about an inch in diameter and is the gateway into the ocean of chi. Around the Hara and with it as the center there is an envelope of energy called the ‘tan tien’ or Dantien. This tan tien or dantien is a ball of etheric energy about the size of a soccer ball. It is filled from the Hara and is often called ‘the cauldron’ in Taoist alchemical texts. This ball of energy interacts with all the organs and especially the intestines as it is where food is turned into energy. Energy is taken from the food and mixed in the tan tien or cauldron before being distributed throughout the body. Having the Hara open and a full tan tien or dantien is vital for real health and vitality. Unfortunately most people have many Samskaras and energetic blockages in this area and the fullness that should be felt in the tan tien is absent. This is the main cause of many addictions especially to food. Constantly eating and overeating are an attempt to feel full despite a blocked Hara and empty tan tien.
Alchemy Realm 
The physical space where the hara or tanden is located is a couple of inches below the navel, inside the body, closer to the spine than the navel. As mentioned earlier it is not so much the physical space that matters, but the energetic or spiritual aspects represented by these words. In this sense, experience of the hara can be spoken of as simply being hara.
In practical terms we talk of bringing the energy down to the hara. Yet there are many layers to be discovered within this concept of hara, so where exactly are we bringing the energy to?
In training we learn and experience one step at a time. Therefore to make the study of the hara easier to understand it is taught that the tanden is the focus point in the belly while hara is our true nature.
For this reason at a beginner’s level practices and techniques guide the mind to focus on the tanden – helping it not to wander. These practices aid you in gaining a fuller understanding of the tanden as your mind calms and you become less distracted. This is the perfect way to begin your training, and the deeper you go, the more your understanding changes and develops.
After what may take many years of practice, you will begin to experience that the tanden actually becomes hara. This growth in understanding is interlinked with a clearer understanding of who you are. At this point your mind is not focused on one point anymore but merged with everything.
If the mind remains focused at the tanden for your entire spiritual journey, you will become stuck and restricted.
At the point of hara the mind has no place to stay still for it is everywhere, completely in union with the universe, no beginning and no end. It is open and at ease. This is hara, or in other words, you have realized your true nature. Here your mind never hesitates or stops; it is like water, when encountering a rock, it simply flows around obstacles.
The Deeper Meaning of Hara by Bronwen and Frans Stiene 
Term first found: Page 57, HGS Manual