Materialization refers to the phenomenal appearance of solid objects in their physical form from thin air. Materialization is also connected to the spirits obtaining a physical form and making others feel their presence. The adepts were supposed to have miraculous powers which helped in this process.
The materialization process was said to begin by spirits conveying ideas and thoughts to a receptive human (medium). Then slowly the spirits started communicating through sounds such as scraping and tapping wood. At the end came the phenomena of materialization which involved the spirits moving things in the air, appearing as shadows and so on.
The mediums themselves were considered responsible in most cases. Many were considered frauds but were often not conclusively exposed, mainly because most of these events happened in partial darkness.
In the later stages of medium communication, materialization became the aim of many people. The spirits were usually seen in the room dressed in grey or black and looked vague. They were considered to be the spirits of the deceased.
Skeptics continue to assert that materialization is indistinguishable from stage magic.