The Camino de Santiago, or in English, the Way of Saint James, is the name of any of the pilgrim routes to the shrine of the apostle St. James the Great in the Cathedral of Santiago de Compostela, Galicia, Spain. The most common and popular route is Camino Frances, which for the most part is actually in Spain. Many people in mainland Europe walk from their own front door. For some it is a religious journey, for others it is a spiritual journey. Some walk for cultural reasons, some just walk and see what happens.
The scallop shell, which is commonly used as a symbol for the Camino, can act as a metaphor. The grooves in the shell come together at a single point. This represents the various routes pilgrims have travelled to reach Santiago de Compostela.
One of the best sources of practical information about the Camino is this forum, it will answer all the questions you may have about doing a Camino and which one to do. Here is link to it.