A Quantity Surveyor (QS) manages all financial and contractual aspects of construction projects, from initial cost estimates and budgeting to final account settlement, ensuring projects stay within budget and meet quality standards by liaising with architects, engineers, and contractors, handling tender documents, contracts, and monitoring costs on-site. Key duties involve cost analysis, risk management, contract negotiation, financial reporting, and resolving disputes, serving as the financial expert to balance cost with project quality.