A meaningful index is one that clearly identifies each row. The default RangeIndex is not very helpful. Since each row identifies data for exactly one movie, it makes sense to use the movie title as the label. If you know ahead of time which column will make a good index, you can specify this upon import with the index_col parameter of the read_csv function.

By default, both set_index and read_csv drop the column used as the index from the DataFrame. With set_index, it is possible to keep the column in the DataFrame by setting the drop parameter to False.