1. A method for displaying and sending messages including both standard and custom characters, the method comprising: (a) accepting and displaying, via a user interface of a client device, a message within a message entry field, wherein the message includes one or more standard characters and one or more custom characters that are selected by a user of the client device, a unique custom character reference, one or more tag words, and image data are associated with each of the custom character(s), each of the standard character(s) is included within a Unicode Standard, and each of the custom character(s) is not included within the Unicode Standard; (b) in response to accepting an indication that the user of the client device wants to send the message within the message entry field to a second user of a second client device, sending, from the client device to the second client device, message data that includes the following the one or more standard characters included in the message entry field, the unique custom character reference associated with each of the custom character(s) included in the message entry field, and at least one tag word associated with each of the custom character(s) included in the message entry field; wherein the sending of the unique custom character reference associated with each of the custom character(s) included in the message entry field, from the client device to the second client device, enables the second client device to obtain the image data associated with each of the custom character(s) from a local data store of the second client device or from a remote server, and thus, without the client device sending the image data associated with each of the custom character(s) to the second client device; wherein the standard characters that are included within the Unicode Standard are selectable by the user of the client device via a virtual keyboard of the user interface of the client device; wherein image data for the standard characters that are included within the Unicode Standard are provided by the operating system of the client device, which is stored in a local data store of the client device; and wherein the image data for each of the custom character(s) is not provided by the operating system of the client device.
8. The method of claim 1 , wherein the message entry field comprises a message tray that is displayed via the user interface of the client device, and further comprising: (c) after message data for a message within the message tray is sent from the client device to the second client device, displaying the message for which the message data that was sent within a message bubble that is displayed via the user interface of the client device, with the message bubble being part of a displayed message thread that may or may not already include other message bubbles.