Ordinary least squares (OLS) is a statistical method used to estimate the relationships between variables. It works by finding the line that best fits a set of data points, minimizing the sum of the squared differences between the observed values and the values predicted by the line. This technique is commonly used in regression analysis to understand how one variable affects another. In OLS, the goal is to determine the coefficients of the linear equation that represents the relationship. By applying this method, researchers can make predictions and infer trends, making it a fundamental tool in fields like economics, social sciences, and data analysis.