Is ACH only available in the US?

Could you elaborate on the availability of Automated Clearing House (ACH) transactions beyond the United States? I've heard that ACH is a popular and efficient payment method within the US banking system, but I'm curious if it extends to other regions as well. Does ACH functionality vary significantly from country to country, or is it primarily confined to the US? If it's not exclusively US-based, could you provide an overview of where ACH-like services are available and how they compare to traditional ACH transactions? I'm particularly interested in how international transfers are handled using such systems.