# Concepts

> Declare arguments, configure parsing, and validate user input.

## Documentation

- [Arguments](https://hulla.dev/docs/args/arguments.md): Match the shape of user input with flags, options, positional values, or sequences.
- [Parser options](https://hulla.dev/docs/args/options.md): Control which argv entries are read and how names, aliases, and command arguments are matched.
- [Commands](https://hulla.dev/docs/args/commands.md): Give each CLI command its own arguments, including nested commands.
- [Validation](https://hulla.dev/docs/args/validation.md): Validate command-line values with Zod and handle missing input.