A method comprising: enabling a first user to define a message for display to at least a second user in association with a first three-dimensional scene viewed by the first user and viewed by or viewable by the second user, wherein the message comprises user-defined message content for display and message metadata, not for display, defining first three-dimensional spatial information; and enabling rendering of the user-defined message content in a second three-dimensional scene viewed by the second user, wherein the user-defined message content moves, within the second three-dimensional scene, along a three-dimensional trajectory dependent upon the first three-dimensional spatial information and three-dimensional spatial information of the second user.