Combining DataFrames vertically

There are times when we need to append rows from one data table to another. This will almost always be rows from data tables with similar structures, along with the same columns and data types. For example, we might get a new CSV file containing hospital patient outcomes each month and need to add that to our existing data. Alternatively, we might end up working at a school district central office and receive data from many different schools. We might want to combine this data before conducting analyses.

Even when the data structure across months and across schools (in these examples) is theoretically the same, it may not be in practice. Business practices can change from one period to another. This can be intentional or happen inadvertently due to staff turnover or some external factor. One institution or department might implement practices somewhat differently than another, and some data values might be different for some institutions or missing...