diff --git a/docs/overview/index.rst b/docs/overview/index.rst
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--- a/docs/overview/index.rst
+++ b/docs/overview/index.rst
@@ -1,15 +1,40 @@
-About trusted services
-======================
+Introduction
+============
+
+The term 'trusted service' is used as a general name for a class of application that runs in an isolated
+processing environment. Other applications rely on trusted services to perform security related operations in
+a way that avoids exposing secret data beyond the isolation boundary of the environment. The word 'trusted'
+does not imply anything inherently trustworthy about a service application but rather that other applications
+put trust in the service. Meeting those trust obligations relies on a range of hardware and firmware
+implemented security measures.
+
+The Arm A-profile architecture, in combination with standard firmware, provides a range of isolated
+processing environments that offer hardware-backed protection against various classes of attack. Because
+of their strong security properties, these environments are suitable for running applications that have
+access to valuable assets such as keys or sensitive user data. The goal of the Trusted Services project is
+to provide a framework in which security related services may be developed, tested and easily deployed to
+run in any of the supported environments. A core set of trusted services are implemented to provide basic
+device security functions such as cryptography and secure storage.
+
+Example isolated processing environments are:
+
+    - **Secure partitions** - secure world VMs managed by a secure partition manager
+    - **Trusted applications** - application environments managed by a TEE
+    - **Integrated microcontroller** - a secondary MCU used as a secure enclave
+
+For more background on the type of problems solved by trusted services and how the project aims to
+make solutions more accessible, see:
 
 .. toctree::
     :maxdepth: 1
-    :caption: Contents:
 
-    introduction
+    example-usage
     goals
 
+
+
 --------------
 
-*Copyright (c) 2020-2021, Arm Limited and Contributors. All rights reserved.*
+*Copyright (c) 2020-2022, Arm Limited and Contributors. All rights reserved.*
 
 SPDX-License-Identifier: BSD-3-Clause