An aspect of Devi and a personification of God as the Divine Mother who represents the active, dynamic principles of feminine power.
Shakti (from Sanskrit shak, "to be able"), meaning "Power" or "empowerment," is the primordial cosmic energy and represents the dynamic forces that are thought to move through the entire universe in Hinduism. Shakti is the concept, or personification, of divine feminine creative power, sometimes referred to as 'The Great Divine Mother' in Hinduism. On the earthly plane, Shakti most actively manifests through female embodiment and creativity/fertility, though it is also present in males in its potential, unmanifest form.
Not only is Shakti responsible for creation, it is also the agent of all change. Shakti is cosmic existence as well as liberation, its most significant form being the Kundalini Shakti, a mysterious psychospiritual force. Shakti exists in a state of svātantrya, dependence on no one, being interdependent with the entire universe.
In Shaktism and Shaivism, Shakti is worshipped as the Supreme Being. Shakti embodies the active feminine energy of Shiva and is identified as Tripura Sundari or Parvati.
Example via www.ramdass.org: What is Shakti, or Prana?