What is Pandas and how is it used in data science?

Pandas is a Python library for data manipulation and analysis. It provides two main data structures:

**Series** — 1D labelled array
**DataFrame** — 2D table (like Excel)

```python
import pandas as pd
df = pd.read_csv('data.csv')
df.head() # First 5 rows
df.describe() # Summary statistics
df.isnull().sum() # Count missing values
df.groupby('city')['salary'].mean() # Group aggregation
```

Used for data cleaning, transformation, and analysis.