The Global Maritime Traffic Density Service (GMTDS) provides a public global maritime vessel traffic web-service to disseminate vessel traffic information to the world. GMTDS processes billions of space-borne and terrestrial-based AIS messages for wide user access and societal benefits. GMTDS adapts methods developed by the European Marine Observation and Data Network (EMODnet) for the European Union Region. GMTDS cleans, enriches, and processes raw AIS messages into monthly raster grids at 1-kilometer spatial scale with ship densities measured as hours per square kilometer per month. These rasters are then transferred to a Spatial Data Infrastructure (SDI) where they will be able to be downloaded or accessed via Open Geospatial Consortium (OGC) web services. This document is produced by MapLarge, the GMTDS prime contractor, and reviewed by the NGA GMTDS Program Office and customers within NGA's Maritime Safety Office. Feedback regarding this document can be provided to GMTDS@maplarge.com.