回应 (huí yìng) means 'to respond' in a formal or official context, such as a company, government, or public figure addressing questions or demands. It is more formal than 答应 (dā ying, everyday 'answer/agree') and 反应 (fǎn yìng, 'react' often involuntarily), and it does not imply agreement like 响应 (xiǎng yìng, 'respond to a call/appeal'). Use 回应 when the response is a deliberate, often public statement.