By far the most common spiritual practice not tied to any formal religion is the custom of ancestor worship. The veneration of one's deceased ancestors is especially common in lands populated with humans, half-orcs, half-elves, halflings, orcs, goblinoids, and other relatively short-lived races. The usual form of ancestor worship is to pour libations upon the grave site of the deceased, or to burn incense or spicy foods as offerings in a household shrine. The efficacy of these practices is measurable, since magical travel into the Ethereal Plane (or through it into the Spirit World) reveals that the deceased frequently remain present, fixed to the locations of their graves or familial homes, for extended periods of time when regular offerings and prayers are directed to them.
This is in sharp contrast to the deceased of cultures that do not venerate the dead—in such cultures, it is uncommon for the spirit of the deceased to remain in the Spirit World at all, except as a ghost, specter, or other undead creature which arises spontaneously in response to regrets or trauma incurred in the course of life or dying. In cultures which are characterized by belief in a god or pantheon of gods, the disappearance of the deceased's spirit is attributed to its departure from the Spirit World to the home of one or another of the gods. Ancestor worship, in religiously-orientated cultures, is usually viewed not as a replacement for this afterlife, but as a transitional stage between life and a soul's final rest.
The spirits of ancestor-worshiping families are typically much as they were in life. They are usually interested in the activities and well-being of their descendants, and attempt to safeguard them against spiritual threats—for example, by discouraging night hags and other creatures of ill omen from predating upon the inhabitants of their descendants' houses. They are effectively ghosts who cannot manifest, and in the Spirit World are capable of striving against such creatures with bodily force. Individually an ancestral ghost may not be very powerful, but since most ancestor-worshiping cultures value stability and have well-established inheritance routines, there may be many generations' worth of such spirits in residence.