协议 (xiéyì) is a formal noun meaning 'agreement' or 'protocol'—a written or spoken understanding between two or more parties, often legally or officially binding. The first character 协 (xié) means 'to cooperate' or 'to coordinate', and the second character 议 (yì) means 'to discuss' or 'to deliberate'. Together, they convey the idea of reaching a mutual understanding through discussion and cooperation.

This word is commonly used in diplomatic, business, technical, and legal contexts—for example, international treaties, software communication standards (like HTTP protocol), or workplace contracts. It carries a formal, official tone and is rarely used in casual conversation about personal arrangements (where 约定 yuēdìng or 合同 hétong would be more appropriate). 协议 emphasizes consensus and shared intent rather than unilateral decision-making.