MongoDB is a NoSQL database. This means that unlike the MySQL database we used for our Crime Map project, it is not organized into tables, rows, and columns; instead, it is organized into collections, documents, and fields. While it can be useful to think of these new terms as a sort of translation from those we use for relational databases, the concepts do not perfectly translate. If you have a background in relational databases, a useful and more complete reference to these translations can be found on the official MongoDB website at https://docs.mongodb.org/manual/reference/sql-comparison/.

MongoDB's structure is much more flexible than that of a SQL database—not all of our data has to confirm to a specific schema, and this can save development time. For our Crime Map project, we had to spend time up front looking at our data and deciding how to represent it in a database. We then had to set up a bunch of fields, specifying the data type, length, and other constraints...