# API reference

Start with the public imports. Related functions and classes are documented
together on the topic pages below, with signatures, docstrings, and source links.

```python
from params_proto import proto, EnvVar, Field, get_var, Sweep
```

| Topic | Main APIs | Use it to |
| --- | --- | --- |
| [Configuration](/reference/configuration) | `proto`, `proto.cli`, `proto.prefix`, `proto.bind`, `proto.parse`, `proto.partial` | Declare configuration, expose commands, and apply overrides. |
| [Environment & fields](/reference/environment) | `EnvVar`, `Field`, `get_var` | Read environment values and compute fields. |
| [Parameter sweeps](/reference/sweeps) | `Sweep`, `piter`, `ParameterIterator` | Compose and iterate experiments. |
| [CLI helpers](/reference/cli#params_proto.cli) | `parse_cli_args`, `colorize_help`, `get_terminal_width` | Customize parsing and help output. |
| [Compatibility](/reference/compatibility) | v1 and v2 classes, functions, and sweeps | Maintain code using compatibility APIs bundled with this release. |

Each page starts with a linked API index. Module sections retain the source
context; methods stay with their classes. Lower-level implementation types
are included where they support the public APIs, without separate sidebar pages.

## Examples and earlier versions

For a walkthrough, start with [Quick start](/quick_start),
[configuration patterns](/key_concepts/configuration-patterns), or
[hyperparameter sweeps](/key_concepts/hyperparameter_sweeps).

The compatibility page describes the modules shipped in the selected source
version. Historical guides and earlier builds remain available through the
version selector.