Data cleansing is the process of identifying and correcting errors, inconsistencies, and inaccuracies in a dataset to ensure its quality, accuracy, and reliability. This process is crucial for businesses that rely on data-driven decision-making, as poor data quality can lead to costly mistakes and inefficiencies. By cleansing data (removing duplicates, correcting inaccuracies, and filling in missing information), organizations can improve operational efficiency and make more informed decisions.