A temperature data logger is an electronic device designed to automatically measure and record temperature over time, providing a precise and continuous record of environmental conditions. In medical and pharmaceutical contexts, these devices are absolutely critical for cold chain management, ensuring the integrity and efficacy of temperature-sensitive products like vaccines, medications, blood products, and laboratory samples. Unlike simple thermometers, data loggers store hundreds or even thousands of readings at pre-set intervals, which can then be downloaded to a computer for analysis, visualization, and reporting. They often feature programmable alarm thresholds that trigger visual or audible alerts if temperatures fall outside a safe range, allowing for immediate corrective action. Many modern data loggers are compact, battery-powered, and equipped with a USB interface for easy data retrieval. Some even offer wireless connectivity for real-time monitoring. The data collected by these devices provides an undeniable audit trail, essential for regulatory compliance, quality assurance, and troubleshooting any temperature excursions that could compromise product viability. By providing objective and continuous temperature monitoring, data loggers play a fundamental role in safeguarding patient health and preventing significant financial losses due to spoiled medical supplies.