diff --git a/docs/getting_started/image-terminology.rst b/docs/getting_started/image-terminology.rst
index 5993d6e..a90ec0b 100644
--- a/docs/getting_started/image-terminology.rst
+++ b/docs/getting_started/image-terminology.rst
@@ -92,6 +92,14 @@
 abbreviated name should identify the vendor as well as the image
 function. For example, ``AP_BL3_ARM_RAS``.
 
+Realm Monitor Management Firmware: ``RMM``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This is the Realm-EL2 firmware. It is required if
+:ref:`Realm Management Extension (RME)` feature is enabled. If a path to RMM
+image is not provided, TF-A builds Test Realm Payload (TRP) image by default
+and uses it as the RMM image.
+
 SCP Boot ROM: ``SCP_BL1`` (previously ``BL0``)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~