The document discusses the reasons for the expansion of NoSQL databases. It notes that next-generation data processing is centered around big data and unstructured data, which are difficult to handle with traditional relational databases. NoSQL databases like MongoDB are better suited for schema-less data storage and handling. The main reasons for NoSQL's growth are the rapid expansion of unstructured data and big data. MongoDB Atlas is MongoDB's database as a service offering, which provides an elastic, fully managed NoSQL database in the cloud.