# Extracting extension from filename in Python

You can use the `os.path.splitext()` function from the `os.path` module in Python to extract the file extension from a filename.

Here's an example:

```python
import os
filename = "example.txt"
extension = os.path.splitext(filename)[1]
print(extension)
```

This will output: `.txt`

Alternatively, you can use string slicing to extract the file extension.

```python
import os
filename = "example.txt"
extension = filename[filename.index(".")+1:]
print(extension)
```

This will also output: `.txt`