“Nibbana is the end of samsara. Contrary to a popular misunderstanding, neither nibbana nor samsara is a place. In attaining nibbana we don’t escape from one location to another. For the Buddha, samsara is the process by which clinging gives rise to suffering which, in turn, gives rise to further clinging. He understood that this self-perpetuating process continues over lifetimes as the “fuel” for rebirth, just as the fire from one burning house is carried to a neighboring house by the wind. Nibbana is what is realized when the clinging of greed, hate, and delusion is brought to an end. Some later Buddhist traditions equate nirvana and samsara. However, they likely attribute very different meanings to these words than those understood by the earliest Buddhist tradition. In Theravada teachings, samsara cannot be nibbana any more than a clenched fist can be an open hand, any more than burning ember in your fist can be the same as letting it go. For the Buddha, nibbana had quite positive associations – after all, it is a simile for ultimate freedom and awakening. At times he used other similes to describe this state: “the blissful, the secure, the pure, the island, the shelter, the harbor, the refuge, the ultimate.”

Other, more perplexing, synonyms include “the unconstructed, the ageless, the deathless, the featureless.” These refer to the idea that nibbana does not exist as something that can be made, shaped, or willed. It is not a “ground of being” from which anything subject to death can arise. Although there is a consciousness, “featureless, infinite, and luminous all around,” that is associated with nibbana, it is not dependent on the conditioned world. Nor does it produce the conditioned world. Rather, it is a dimension of consciousness totally independent of circumstances in the world or in one’s personal life. Because nibbana is independent, people who fully realize it are said to be “unestablished” – in other words, free from any clinging that would confine their consciousness to any point in space or time. ”

http://www.tricycle.com/feature/nirvana-three-takes