**Lesson Summary:**

One of Python's great strengths is that it comes with a standard library containing many useful modules. In this lesson, we'll learn the various ways that we can use modules, and we'll also take a look at some of the commonly used modules.

#### Documentation For This Video

#### Using Standard Library Modules

We've already utilized a standard library package when we used the `math`

module to calculate the circumference of a tire. We used one of the variables from the `math`

module in the form of `pi`

, but we loaded the entire module using this line:

```
import math
```

Using `import`

we're able to access the internals of the module, by chaining off of the module's name as we did with `pi`

using `math.pi`

, but there are other ways we could have accessed `pi`

. Let's take a look at some of our options:

`from math import pi`

- We can access `pi`

by itself, and we can't reference `math`

because we used a selective import.`from math import pi as p`

- This would allow us to have access to a `p`

variable that contains the value of `pi`

.`from math import pi, floor, ceil`

- This would selectively import the `pi`

variable, the `floor`

function, and the `ceil`

function.`from math import *`

- This would import *EVERYTHING* (except names starting with an underscore) from the `math`

module into the current namespace. Avoid doing this if possible.

#### Useful Standard Library Modules

Here are some of the most useful standard library modules that we'll use throughout the remainder of the course.

`argparse`

- for creating CLIs`json`

- for working with JSON`math`

- for doing math operations`os`

- for interacting with operating system resources`pdb`

- the Python debugger`sys`

- for interacting with system specific parameters and functions