An online data catalog is a digital platform that provides researchers, data scientists, and other stakeholders with access to a wide range of datasets for various research purposes. These catalogs typically contain organized and searchable collections of data from different sources, including government agencies, research institutions, and private organizations. Users can browse through the catalog to find datasets that are relevant to their research interests, and then download the data for further analysis. Online data catalogs often feature metadata descriptions, data documentation, and data quality information to help users understand the contents and context of the datasets. Overall, online data catalogs play a crucial role in enabling data-driven research by simplifying the process of discovering, accessing, and utilizing diverse datasets for scientific, academic, and business purposes.