diff --git a/README.md b/README.md
index ca3d00e..93dd71f 100644
--- a/README.md
+++ b/README.md
@@ -13,7 +13,7 @@ composer require open-solid/bus
 ### Dispatching Message with the Bus
 
 Think of the "bus" as a mail delivery system for your messages. It follows a specific path, decided 
-by some rules (middleware), to send your messages.
+by some rules (middleware), to send your message and handle it.
 
 Here's a snippet on how to set it up and dispatch a message:
 
diff --git a/src/Envelope/Message.php b/src/Envelope/Message.php
index 54a1fe2..1a55ba8 100644
--- a/src/Envelope/Message.php
+++ b/src/Envelope/Message.php
@@ -13,6 +13,9 @@
 
 namespace OpenSolid\Bus\Envelope;
 
+/**
+ * A data structure that represents a message to be dispatched by a bus to its handlers.
+ */
 abstract readonly class Message
 {
 }
diff --git a/src/Envelope/Stamp/HandledStamp.php b/src/Envelope/Stamp/HandledStamp.php
index d8ea7df..bd40996 100644
--- a/src/Envelope/Stamp/HandledStamp.php
+++ b/src/Envelope/Stamp/HandledStamp.php
@@ -13,6 +13,9 @@
 
 namespace OpenSolid\Bus\Envelope\Stamp;
 
+/**
+ * A stamp that marks the message as handled.
+ */
 final readonly class HandledStamp extends Stamp
 {
     public function __construct(
diff --git a/src/Envelope/Stamp/Stamp.php b/src/Envelope/Stamp/Stamp.php
index 856d5af..53e43d9 100644
--- a/src/Envelope/Stamp/Stamp.php
+++ b/src/Envelope/Stamp/Stamp.php
@@ -13,6 +13,10 @@
 
 namespace OpenSolid\Bus\Envelope\Stamp;
 
+/**
+ * A stamp is a marker that can be used to store metadata and take decisions
+ * during the message journey.
+ */
 abstract readonly class Stamp
 {
 }
diff --git a/src/Envelope/Stamp/Stamps.php b/src/Envelope/Stamp/Stamps.php
index e6afd02..bda5ff0 100644
--- a/src/Envelope/Stamp/Stamps.php
+++ b/src/Envelope/Stamp/Stamps.php
@@ -13,6 +13,9 @@
 
 namespace OpenSolid\Bus\Envelope\Stamp;
 
+/**
+ * A collection of stamps.
+ */
 final class Stamps implements \Countable
 {
     /**