A materialization is the creation or appearance of matter from nowhere and out of nothing. Some miracles involve materializations. The existence of the paranormal phenomenon of materializations is disputed and has never been observed under controlled circumstances. Materializations would break generally accepted scientific laws such as the conservation of energy.
The most famous example of a materialization in Christianity is the story of the multplication of bread and fish by Jesus to feed a hungry crowd, according to the Bible (John 6:1-15 & Mark 6:35-44).