The following information is taken from the book of Jean ROMNICIANU Randonnée Ultra légère, guide pratique available for purchase on his site www.sahibvoyageur.fr
The map is the basis of orientation. Today, it can be in paper form or as an electronic file that displays on your smartphone. A paper version remains the best solution for a global vision of your hike, for its preparation or to learn how to use a map well.
In the field, a board doesn't break or run out of battery, but it's heavy. Above all, it does not indicate where you are.
Do not confuse topographic maps, which you need because they describe the terrain, and the road map which describes the roads and much less the terrain.
In France, the National Institute for Geographic and Forest Information (IGN) offers excellent topographic coverage, both on paper and electronically.
The maps Google Maps or OpenStreetMapwhich are above all road maps, do not sufficiently represent the terrain.
The more difficult the terrain, the more accurate your map should be. With paper, you will use 1/25,000 scale in the mountains, or 1/75,000 scale in easier terrain.
The electronic maps change scale, between 1/25,000 scale and 1/100,000 scale, depending on the magnification adopted on the screen. The level of detail also changes according to this zoom level.
If you want the precision of a map at 1/25,000 scale, you must enlarge the map to obtain a scale bar of 500 meters or less. Naturally, the area covered becomes smaller : this is the major drawback of these maps.
To download a map, you must first download the navigation software (app). These apps are free or inexpensive.
There are many smartphone navigation apps, the best known of which, in France, are Visorando and IGNrando.
All these apps offer free trial periods : take advantage of them and select the one that suits you the most.
Once the app is downloaded, you often have to take out an annual subscription of around 25 euros, which gives you access to the maps.
In France, prefer IGN topographic maps.