Array and Series shapes: the table before the table

In NumPy and pandas, shape is not trivia. Shape tells you whether you have one feature vector, one column, or a full table.

A Series is one named column of values. A DataFrame is a table: rows plus columns. Before you worry about a model, ask whether every row has the same columns and whether every feature has the same number of values.

The browser drills use dictionaries instead of pandas so the habit is visible. Your job is to catch shape drift before it reaches training.