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

# Contacts - Concepts

> Learn key concepts about contacts in Arnio.

# Contacts - Concepts

Learn key concepts about contacts in Arnio.

## Contact properties

Each contact in Arnio has various properties that you can use for segmentation and personalization:

### Standard properties

* **Phone number**: Primary contact identifier for iMessage/SMS
* **Email**: Email address for email campaigns
* **First name**: Customer's first name
* **Last name**: Customer's last name
* **Created date**: When the contact was added
* **Last activity**: Last interaction with your business

### Custom properties

Add custom properties specific to your business:

* Product preferences
* Purchase history
* Subscription tier
* Geographic location
* Any other relevant data

## Subscription status

Manage contact subscriptions for different channels:

* **Subscribed**: Contact has opted in for messages
* **Unsubscribed**: Contact has opted out
* **Pending**: Subscription status pending confirmation

## Contact sources

Contacts can be imported from:

* **API**: Programmatically add contacts via API
* **CSV import**: Upload contacts from spreadsheet
* **Integrations**: Sync from connected platforms (CRM, e-commerce)
* **Manual entry**: Add contacts manually in dashboard

## Contact deduplication

Arnio automatically deduplicates contacts based on:

* Phone number (primary identifier)
* Email address
* Custom unique identifiers

## Contact segments

Organize contacts using:

* **Lists**: Static collections of contacts
* **Segments**: Dynamic groups based on conditions
* **Tags**: Label contacts for organization

**See also:**

* [Contacts →](/audience/contacts)
* [Lists and segments →](/audience/lists-segments)