The history of the pilgrimage retraces the route the apostle James the Great to his final resting place. St. James' body was taken to Galicia by boat from Jerusalem and carried inland to where Santiago de Compostela, now is located. The pilgrimage is believed by some to be one of three pilgrimages which if taken the sins of the pilgrim would be forgiven. There is no specific route which a pilgrim must take, however, the most popular route begins in France's Saint-Jean-Pied-de-Port, the Camino Frances.
While most of the route is fairly gentle with only a few long ascents, some days can be challenging. Over the past 20 years a great deal of effort has gone into improving the walkers' route, and most of the route is now well marked, reasonably well surfaced, and separated from the increasingly heavy traffic on Spanish highways. If one begins in France, the route passes over two major mountain chains and several smaller ones. There is a joke that the Camino never meets a mountain it doesn't cross. While that is not really true, there are many ascents and descents, and some of the latter can be quite steep.
One needs to be in reasonably good condition and to have good hiking boots. It is necessary, if you wish to go camping, to carry clothing and a sleeping bag in a comfortable backpack. Or you can stay in youth hostels ('albergues') for low cost. Unless one plans to camp in the most crowded months of the summer season, it is unnecessary to carry camping and cooking gear.
While many pilgrims only do that final portion of the route, there are great rewards for starting much further away. Some Europeans walk from their homes, following one of the many routes from virtually all corners of central and western Europe. Most of those routes, save the maritime one from the UK and the routes from Portugal and those from southern Spain, converge to channel walkers across one of two Pyrenees passes, Somport or the route between St. Jean Pied-de-Port and Roncesvalles. A few days onward, those two routes converge at Puente la Reina and follow the traditional Camino Frances across Navarra, Castilla-La Mancha, over the pass at O Cebreiro and on to Santiago.
If one has the time and inclination, there are several lovely routes across France leading to Somport and St. Jean Pied-de-Port, the most popular the Chemin St. Jacques beginning at Le Puy-en-Velay and passing through Conques enroute to St. Jean Pied-de-Port. Another French route, the Chemin de Arles passes through the southern tier of Languedoc toward Oloron St. Marie and the pass into Spain at Somport. While those routes are beautiful and interesting in themselves, they add weeks to the already long pilgrimage.
Since a month is a long time, many non-Europeans begin at St. Jean Pied-de-Port or Roncesvalles. Beginning in the French city means the first day of walking requires a long and steep climb, perhaps the most arduous single day on the route. Steeped in history, the site of the defeat and death of Charlemagne's lieutenant Roland, Roncesvalles is a usual starting point for Spaniards.