Update: It looks like the map in question really came from Prima's digital strategy guide, available here. Sorry, wasteland looters - you'll have to get this one with your real currency.
I don't know if you've noticed this about Fallout 4 yet, but there's a whole lot of it. The Commonwealth is geographically tiny next to the worlds of GTA 5 or The Witcher 3, but it's stuffed to the mirelurk gills with settlement sites, raider camps, and darkly humorous skeleton arrangements. This map will help you plot out a perfect tour of the Commonwealth ahead of time.
It's true, your Pip-Boy has a built-in world map, but it's not half as comprehensive as the one supposedly made by Reddit user koolkyle802 (which is a terrific username, by the way). On top of points of interest like cities, vaults, and bobblehead locations, it even has color-coded threat levels so you can dress and arm yourself appropriately for any given area.
If you'd rather experience the Commonwealth fresh (or as fresh as an irradiated, mutant-infested Wasteland can be, anyway), scroll no further. Or if you want the full, high-res map for future consultation, download away.