Natural Earth
Natural Earth is a curated set of map data designed to make good-looking maps at small and medium scales. Rather than aiming for exhaustive detail, it focuses on clean, consistent features that render well, which is why it is a favourite for world and regional maps in newsrooms, atlases, and data visualisations.
The cultural themes cover country and state boundaries, populated places, roads, railways, and airports. The physical themes cover coastlines, rivers, lakes, glaciers, and bathymetry. Vector data ships as shapefiles and the raster data as GeoTIFF, and everything is released into the public domain with no attribution required.
For RAG, Natural Earth is a light, dependable source of administrative boundaries and place names when you do not need the fine detail of OpenStreetMap. You can download themes individually or as full packages straight from the site.
Related sources
GeoNames
A geographical database of more than 11 million place names, each with coordinates, population, elevation, and administrative divisions, covering every country. It works well as a gazetteer for resolving place names to locations.
OpenStreetMap
A crowdsourced map of the world, built and maintained by a community of volunteers. It holds detailed geographic data on roads, buildings, land use, points of interest, and much more, which you can download as a full planet file or as smaller regional extracts.
Overture Maps Foundation
An open map data project run under the Linux Foundation by a group of industry members. It combines and harmonises data from OpenStreetMap, Microsoft, Meta, and others into consistent, interoperable map layers you can build on freely.