Byzantine silk is a special type of cloth that was made a long time ago in a place called Byzantium, which is now called Istanbul. It was very popular and expensive because it was made from a very special material called silk, which comes from tiny little worms called silkworms.
Silkworms spin a special thread that is very strong and shiny, which is why people like to use it to make clothes. But making silk cloth is not easy, it takes a lot of work and skill. The people who made Byzantine silk were very good at it and they had a special way of weaving the threads to make beautiful patterns.
Today, people still love Byzantine silk because it is so pretty and unique. But because it is so rare and expensive, not many people can afford to have it. But we can still look at pictures of it and admire its beauty.