The Self has two primary qualities. Though they are essentially one, we speak of them as two. They are Shiva and Shakti. These two words do not refer to the personified deities in the Hindu pantheon, but are used metaphorically in the tantras to refer to the two essential qualities of the Self: Pure Being (Shiva) and Dynamic Creative Potential (Shakti).
The Hindu god Shiva is the perfect yogi, always immersed in oneness with the Self. So metaphorically the tantras speak of the eternally-
Shakti and kundalini
But the Self is also dynamic creative potential and this is metaphorically called Shakti. Shakti is often translated as "energy", but that is a poor translation since energy is of the relative, while Shakti is of the Absolute. Shakti first separates from Shiva in a diminiscule contraction known as bindu (infinitely small spot) and this bindu manifests as what is knows as kundalini. Kundalini then manifests you as an ignorant individual during your period as a foetus and an infant. Kundalini then retreats into a small bulb-
There is NO difference between Shiva and Shakti, but you have to be enlightened to a rather high degree to understand this. Shakti contracts into kundalini and manifests you as an ignorant structure, but in doing so it keeps secretly within itself the key to undoing your ignorance and granting you enlightenment.
I will write more aout shaktipat later. But it is a way to awaken kundalini so it begins to use its inherrent knowledge of your ignorance to undo your ignorance and grant you full enlightenment.