Cost-benefit analysis is a decision-making tool used to evaluate the potential advantages and disadvantages of a project or investment. It involves comparing the total expected costs of an action, such as building a new bridge, against the total expected benefits, like reduced travel time and improved safety. By quantifying these factors, individuals and organizations can determine whether the benefits outweigh the costs. This analysis helps in making informed choices by providing a clear picture of the financial implications. For example, a city considering a new public transportation system would assess the costs of construction and maintenance against the benefits of reduced traffic congestion and lower pollution levels.