This report is a summary of some of the information that was assembled and presented in final report FHWA-TS-90-043 entitled, 'Guidelines on the Use of Changeable Message Signs". The final report provides guidance on 1) selection of the appropriate type of CMS display, 2) the design and maintenance of CMSs to improve target value and motorist reception of messages, and 3) pitfalls to be avoided, and it updates information contained in the 1986 FHWA publication "Manual on Real-Time Motorist information Displays." The guidelines and updated information are based on research results and on practices being employed by highway agencies in the United States, Canada and western Europe. CMS technology developments since 1984 are emphasized. This summary report focuses on matrix-type CMSs, with particular attention to the newer light-emitting signs. Although there are many types of new and emerging CMSs technologies, CMSs that have actually been installed for highway applications are emphasized.