The Camino de Santiago is in general a well-marked route; there is normally no doubt about what itinerary to follow.
The most profuse and characteristic signs on the road are the yellow arrows, they are painted everywhere. These arrows are usually placed in the intersections, always in visible places such as: traffic signs, on the pavement, in a tree, in a stone, etc.
When you are walking the Camino, you will see these signs, it is important to pay attention so that you do not go off route, especially if you are doing the Camino by bicycle. Notice that some of them can be worn, or partially covered by vegetation over time.
Yellow arrows are not the only signs on the Camino. There are some points where the Camino crosses, or concurs with other roads; there you will find some vertical blue metallic signs, with the anagram of the Camino (a yellow scallop shell), the shape of a walker, and a white arrow.
The most abundant signs on the trails of the Camino will be the yellow arrows, but given that the Camino is also the GR65 walking route, you will also find the distinctive marks of the Long-Distance Trails: two small strips of white and red paint.
The villages and cities throughout the Camino will also have signs; they will be on walls of old houses or buildings, they are little blue ceramic tiles with the yellow scallop shell.
In spots where there are sudden changes in the route, you will encounter stone cairns with these same ceramic plates; some will have the distance to Santiago de Compostela.
Be very careful when you pass by crossings and when you go through mountain paths; It is very easy to miss the signs and get lost.