diff --git a/glossary.asciidoc b/glossary.asciidoc
index d9018dd..e99f8f7 100644
--- a/glossary.asciidoc
+++ b/glossary.asciidoc
@@ -182,6 +182,12 @@ ephemeral key::
     This increases the security of transported messages or payments.
     Even if an ephemeral key leaks, only information about a single payment becomes public.
 
+feature bits::
+    A binary string that Lightning nodes use to communicate to each other which features they support.
+    Feature bits are included in many types of communication, such as invoices or channel announcements.
+    They can be decoded using BOLT #11, and will tell nodes which features the node has enabled, and whether these are backwards-compatible.
+    Also known as feature flags.
+
 fees::
     In the context of Bitcoin, the sender of a transaction includes a fee paid to miners for including the transaction in a block. 
     In the context of the Lightning Network, nodes will charge routing fees for forwarding other users' payments.