The term 'data lake' refers to a centralized repository that stores vast amounts of structured, semi-structured, and unstructured data in its native format. In big data architecture, data lakes allow organizations to retain raw data for future analysis without the constraints of traditional databases. This flexibility enables data scientists and analysts to perform exploratory analytics, machine learning, and data mining. Data lakes support diverse data types and encourage a data-driven culture by making information readily accessible and actionable.