Why do so many coins’ symbols start with ‘X’?

You may have noticed that many cryptocurrencies have alpha codes that begin with an ‘X’. Examples include Ripple – XRP, Monero – XMR, Stellar – XLM, and many more. You may even notice that Bitcoin, typically BTC, is listed as XBT in some cases.

This is no coincidence. The ISO (International Standard for Organization) defines alpha codes and numeric codes. ISO 4217 provides code for supranational currencies. For these currencies without one defined country, an X is prefixed to its code. This is an old standard, but it’s universally recognized, avoiding confusion for users. There is no central authority enforcing an alpha code system, it’s just done for organization and readability.