# How do I get a substring of a string in Python?

To get a substring of a string in Python, you can use the string slicing notation, which is `string[start:end]`, where `start` is the index of the first character of the substring, and `end` is the index of the character just after the last character of the substring. For example:

```python
string = "Hello, world!"
substring = string[7:12]
print(substring)
```

This would output `"world"`.

If you omit the `start` index, the substring will start from the beginning of the string. If you omit the `end` index, the substring will continue to the end of the string.

You can also use negative indices to specify the `start` and `end` indices relative to the end of the string, with `-1` being the last character, `-2` being the second-to-last character, and so on.

For example:

```python
string = "Hello, world!"
substring = string[-5:]
print(substring)
```

This would also output `"world"`