Style guide: media

wiki/src/contribute/how/documentation/style_guide.mdwn

@@ -120,6 +120,24 @@
   And not *graphics adapters*, *graphics*, *graphical hardware*, or
   *video card*.
 
+- **media** and **installation media**
+
+  Use only in rare occasions where it is especially relevant to mention
+  both USB sticks and DVDs.
+
+  Tails is now primarily advertised for USB sticks. We prefer making our
+  text easy to read for the majority of people using USB sticks than to
+  be exhaustive and always mention DVDs, implicitly or explicitly.
+
+  - *For example*:
+
+    - Tails runs on a USB stick that you can plug in and use on almost
+      any computer.
+
+    - It is not possible to install Tails on a hard disk. Tails is
+      designed to be a live system running from a removable media: USB
+      stick or DVD.
+
 - **network interface**, **Wi-Fi interface**
 
   And not *card*, *device*, or *adapter*.