---
title: Synchronization overview
description: Synchronization keeps data consistent across disparate resources. Within IDM, we refer to two resource types—managed resources (stored in the IDM repository) and external resources. An external resource can be any system that holds identity data, such as PingDS (DS), Active Directory, a CSV file, a JDBC database, and so on.
component: pingidm
version: 8.1
page_id: pingidm:synchronization-guide:sync-overview
canonical_url: https://docs.pingidentity.com/pingidm/8.1/synchronization-guide/sync-overview.html
keywords: ["Synchronization", "Types"]
---

# Synchronization overview

*Synchronization* keeps data consistent across disparate resources. Within IDM, we refer to two resource types—*managed resources* (stored in the IDM repository) and *external resources*. An external resource can be any system that holds identity data, such as PingDS (DS), Active Directory, a CSV file, a JDBC database, and so on.

IDM connects to external resources through [*connectors*](https://docs.pingidentity.com/openicf/connector-reference/preface.html). Synchronization across resources happens when managed resources change or when IDM discovers a change on a system resource. There are various [synchronization mechanisms](sync-types.html) that ensure data consistency.