What it is: the person who gives the power in a power of attorney — the one initiating and signing the legal document. If you sign a POA, you are the principal.
Why it matters: the principal defines the scope — the agent can only act within the authority the document (signed by the principal) grants. A POA is personal to the principal; it ends at death, and its authority is limited by its terms.
What the principal controls: which powers to grant, who the agent is, whether it’s durable, and when it takes effect (immediately or only on incapacity).
Watch out for: as principal, you can revoke the POA at any time while competent — in writing, and you should notify the agent and any institutions that relied on it. A revoked POA that’s still floating around can cause confusion; reclaim or destroy the old original.