This document provides an introduction to non-relational (NOSQL) databases. It discusses object-based databases and storing objects in SQL databases. It also covers different NOSQL data models like Neo4j which is a graph database, and MongoDB which is a document-oriented database. The document describes some key differences between SQL and MongoDB concepts like databases, tables, collections, documents, and indexes. It provides an example of embedding documents and linking in MongoDB as an alternative to table joins in SQL.