> ## Documentation Index
> Fetch the complete documentation index at: https://docs.athina.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Concepts

> Learn the basics of flows and blocks.

## Flows

A flow is a sequence of blocks that are executed in order.

## Blocks

A block is a single step in a flow.

## Variables

Variables can be used to pass data between blocks.

**Inputs** are variables that are passed to the flow when it is run.

Learn more about variables in [Variables in Flows](/flows/variables).

## Notebook

Flows are laid out as notebooks in the UI.

We describe Flows as **"Low-code notebooks for LLM engineering"**.

You can add headers, text blocks, images, comments and more to
your notebooks to make them more readable and useful for people you share them with.

These notebooks can be a great way to prototype different ideas, collaborate with your team, or even to [share publicly](/flows/share-flows) as executable tutorials / docs.