Sola gratia, meaning 'by grace alone,' is a theological principle that emphasizes salvation as a gift from God, completely unearned and not dependent on human efforts or merits. This concept is central to many Protestant denominations, particularly in the context of the Reformation, and asserts that grace is the sole means through which individuals receive salvation, highlighting the unconditional love and mercy of God. It underscores the belief that human beings cannot achieve redemption through their own actions but rely solely on divine grace.