26. The server system of claim 24 , wherein the server messaging application is also operable to: receive from a said client device associate with a said user, image data associated with a new custom character created by the user and one or more tag words that the user specified as being associated with new custom character; store within at least one of the one or more data stores, a unique custom character reference for the new custom character, the one or more tag words associated therewith, and the image data associated therewith.
24. A server system, comprising: one or more processors; one or more data stores configured to store client data for each of a plurality of clients that are each associated with a respective client device; a unique custom character reference, one or more tag words, and image data associated with each of a plurality of custom characters; and a server messaging application including instructions that are executable by the one or more processors, the server messaging application operable to: receive a unique custom character reference query including one or more standard characters from a said client device, and in response thereto, identify one or more of the unique custom character references that have a tag word associate therewith that includes the one or more standard characters included in the unique custom character reference query; send to the client device from which the unique custom character reference query was received, a list of the identified one or more of the unique custom character references that have a tag word associate therewith that includes the one or more standard characters included in the unique custom character reference query; receive an image data query including a unique custom character reference from the client device, and in response thereto, identify image data for a custom character associated with the unique custom character reference included in the image data query; and send to the client device from which the image data query was received, image data for the custom character associated with the unique custom character reference included in the image data query; 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.