Overview of Data preprocessing and feature engineering, including:

• Numerical/categorical data types. This is a bit of review from Python 100.
• The need for scaling (standardization, normalization).
• Encoding categorical features (one hot encoding)
• Creating new features (again review from Python 100 but that's ok).
• Dimensionality reduction (PCA).

PCA is the most important new concept here, which will be used a lot in later lessons.