Peer review has existed in some form since ancient Greece, but the modern system developed over centuries. The earliest documented peer review process was in 9th century Syria where physician's notes would be reviewed by a medical council. However, most histories of peer review focus on developments since the 18th century in scientific journals and societies. The Royal Society of London began formally requiring peer review of papers in 1663. Electronic peer review began in the early 1990s with new online academic journals. Open access publishing aims to make research freely available to all.