diff --git a/crates/bevy_input/src/button_input.rs b/crates/bevy_input/src/button_input.rs
index 8e4c05e4b9e2a..f4c2bf4b1f83e 100644
--- a/crates/bevy_input/src/button_input.rs
+++ b/crates/bevy_input/src/button_input.rs
@@ -29,6 +29,15 @@ use bevy_ecs::schedule::State;
 /// * Using [`ButtonInput::clear_just_pressed`] or [`ButtonInput::clear_just_released`] instead.
 /// * Calling [`ButtonInput::clear`] or [`ButtonInput::reset`] immediately after the state change.
 ///
+/// ## Window focus
+///
+/// `ButtonInput<KeyCode>` is tied to window focus. For example, if the user holds a button
+/// while the window loses focus, [`ButtonInput::just_released`] will be triggered. Similarly if the window
+/// regains focus, [`ButtonInput::just_pressed`] will be triggered. Currently this happens even if the
+/// focus switches from one Bevy window to another (for example because a new window was just spawned).
+///
+/// `ButtonInput<GamepadButton>` is independent of window focus.
+///
 /// ## Note
 ///
 /// When adding this resource for a new input type, you should: