You can easily modify DataFrames by adding or deleting columns, changing values, or applying transformations.

1. Adding a New Column

To add a new column, you simply assign a list or a scalar value to a new column name.

df['Country'] = ['USA', 'USA', 'USA']
print(df)

2. Modifying Existing Data

You can modify data by referencing specific rows and columns:

df.at[1, 'Age'] = 32  # Modify a specific value
df['Age'] = df['Age'] + 1  # Apply a transformation to an entire column
print(df)

3. Deleting Columns

To delete a column, use drop:

df = df.drop('Country', axis=1)  # axis=1 refers to columns
print(df)

4. Deleting Rows

To delete rows, use drop with axis=0 (default):

df = df.drop(1, axis=0)  # Drop the second row (index 1)
print(df)