# Python Zoneinfo Module

The `zoneinfo` module provides a concrete time zone implementation to support the IANA time zone database. It was introduced in Python 3.9 to replace the need for third-party libraries like `pytz` for most use cases.

## Importing the Module

```python
from zoneinfo import ZoneInfo
```

## Basic Usage

To use a time zone, you create an instance of `ZoneInfo` with the key of the time zone (e.g., "America/New_York", "Europe/London", "UTC").

```python
from zoneinfo import ZoneInfo
from datetime import datetime

# Create a datetime object with a specific time zone
dt = datetime(2023, 10, 31, 12, 0, 0, tzinfo=ZoneInfo("America/Los_Angeles"))
print(dt)
# Output: 2023-10-31 12:00:00-07:00
```

## Converting Time Zones

You can convert a timezone-aware datetime object to another time zone using `astimezone()`.

```python
# Convert to UTC
dt_utc = dt.astimezone(ZoneInfo("UTC"))
print(dt_utc)
# Output: 2023-10-31 19:00:00+00:00

# Convert to Tokyo time
dt_tokyo = dt.astimezone(ZoneInfo("Asia/Tokyo"))
print(dt_tokyo)
# Output: 2023-11-01 04:00:00+09:00
```

## Available Time Zones

You can get a set of all available time zones using `zoneinfo.available_timezones()`.

```python
import zoneinfo

available = zoneinfo.available_timezones()
print(f"Number of available time zones: {len(available)}")

if "Europe/Paris" in available:
    print("Europe/Paris is available")
```

## Data Source

By default, `zoneinfo` uses the system's time zone data. If no system data is available (e.g., on Windows), it looks for the `tzdata` package from PyPI.

```bash
pip install tzdata
```

[[programming/python/python]]