The Pauli-Y gate is a fundamental quantum gate used in quantum computing. It is one of the three Pauli gates, which also include the Pauli-X and Pauli-Z gates. The Pauli-Y gate operates on a single qubit and performs a rotation of 180 degrees around the Y-axis of the Bloch sphere. This transformation changes the state of the qubit, effectively flipping its phase. When applied to a qubit in the state |0⟩, the Pauli-Y gate transforms it into the state |1⟩, and vice versa. Additionally, it introduces a phase shift, resulting in a complex change in the qubit's state. The Pauli-Y gate is essential for creating quantum algorithms and manipulating qubit states in quantum circuits.