diff --git a/docs/index.rst b/docs/index.rst
index ff41bc7..76f8f3f 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -1,17 +1,55 @@
-Welcome to TF-A Unit Tests's documentation!
-===========================================
+Trusted Firmware-A Unit Test Documentation
+==========================================
 
 .. toctree::
-   :maxdepth: 2
-   :caption: Contents:
+   :maxdepth: 1
+   :hidden:
+   :numbered:
+
+   Home<self>
+   user_guide
+   implementing_tests
+   components/index
 
    contributing
-   build_instructions
-   software_requirements
-   user_guide
+   glossary
+   license
+
+This repository contains the unit testing system and the unit tests of the
+`Trusted Firmware-A`_ (TF-A) project. These tests are meant to run on host
+machine and used to cover platform independent code on the unit test level. In
+this case a unit is considered to be a C function or couple related functions.
+Each unit test suite compiles into a binary which can be run and debugged as any
+ordinary executable.
+
+The system uses CppUTest as unit testing framework. The tests are written in C++
+in order to be able to use CppUTests' all useful features like the automatic
+collection of test cases and the CppUMock mocking system.
+
+Separating dependencies apart from the code under test is a crutial step in unit
+testing systems. In many cases this can be easily done by linking mocked
+functions to the tested code but sometimes it's difficult like when the code
+under test and its dependencies are in the same compilation unit. For separating
+the code under test from its dependencies a tool called c-picker can be used. It
+can pick pieces of code (functions, variables, etc.) based on descriptor files.
+
+The build system is based on CMake. The repository contains CMake modules for
+defining unit test suites. It also invokes c-picker if a descriptor file is
+listed among the test sources. CMake has a built in test driver system called
+ctest. It runs all the test binaries and produces an well structured output.
+Test filtering and parallel test run is also available.
+
+For measuring unit test coverage lcov is utilized. The coverage of c-picker
+generated sources is mapped to the original sources files. Coverage currently
+only works with GCC.
+
+As a next step start with reading the :ref:`User guide` and the
+:ref:`Implementing tests` section of this manual. For detailed description of
+the components check the :ref:`Component user manuals` section.
+
 
 --------------
 
-*Copyright (c) 2019, Arm Limited and Contributors. All rights reserved.*
+*Copyright (c) 2019, Arm Limited. All rights reserved.*
 
-SPDX-License-Identifier: BSD-3-Clause
+.. _`Trusted Firmware-A`: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/about
\ No newline at end of file