These are like eBay or Amazon, where the sale of products is conducted. Mostly on the deep web these are used for illegal drug sales (approximately 80%) and the remainder is made up of stolen credit cards, social security numbers, passports, ids, pirated software, dumps of documents, and other miscellaneous items. This is an ever-changing landscape due to many governmental initiatives to remove them, so the addresses, names, and details are always influx and non-permanent.