Reliability refers to the consistency and dependability of a system, product, or service. It indicates how well something performs its intended function over time without failure. For example, a reliable car starts every time and requires minimal repairs, ensuring that the owner can depend on it for daily transportation. In research and statistics, reliability measures the stability of a test or measurement tool. A reliable survey yields consistent results when repeated under similar conditions, allowing researchers to trust the data collected. High reliability is essential for making informed decisions based on accurate information.