A directional light and a spot light casting onto the same ground, side by side. It is the light's side of shadows: whether it casts at all, and the resolution, bias and softness underneath that.
Examples
Every one of these opens in the browser editor, running, with its node graph laid out for you to take apart. Nothing to install and no account needed.
A rigid-body simulation with many objects where your cursor drive one of them, allowing you to interact with the others.
A grid of spheres shaded by a material built node by node. Roughness and metallic are read from point attributes, so the surface changes across the field instead of being one uniform value.
Two objects under one light, and only one of them casts a shadow. Turning that off per object is a pair of parameters: one enables the override, the other carries the value, and setting the value alone does nothing.
geo/ObjectProperties
This example creates a series of objects in a line. If you observe them from either ends of the line, you will see the objects behind the first one are tinted by the ones before them. Their materials' alpha is what makes them see-through. The last one also goes through a geo/ObjectProperties, which sets a transparency mode on that object alone. It is left on AUTO, so the material still decides and the sphere renders like the others. Set it to OPAQUE and that one sphere draws solid, with no change to its material.
geo/ObjectProperties mat/MeshBasic