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

# Define your data structure

> Create the contact fields, tags, and segmentation you need before any client data moves into Assembly.

Take inventory of the systems, spreadsheets, folders, inboxes, and manual processes your team used before Assembly. Decide what information should move into Assembly, what can remain archived, and what does not need to be brought forward.

Create the company and contact fields you will need *before* importing. This makes mapping cleaner and gives your team a consistent structure from the beginning. See [Custom fields](/docs/core-concepts/custom-fields) for how to create and manage them.

## What to bring over

Depending on your operating model, this may include:

* Contact details
* Internal account owner
* Service or client type
* Location
* Lifecycle stage
* Important dates
* Statuses, tags, or other segmentation
* Information used to personalize access or trigger workflows

Tags and other structured fields can power automations and determine which experiences are available to different clients. Keep naming conventions simple, documented, and understandable across your team.

<Warning>
  **Avoid a common mistake:** don't import every historical field simply because it exists. Prioritize information your team will use to serve clients, personalize their experience, trigger workflows, or maintain necessary records.
</Warning>