An electronic platform that allows electronic TRADING of financial or physical ASSETS in cash or DERIVATIVE form. ECNs were popularized during the technology boom of the 1990s and have become a critical element in EXCHANGE and OVERTHECOUNTER trading networks. Advanced ECNs provide for client connectivity realtime pricing, execution, and reporting, and links into automated CLEARING and SETTLEMENT. Also known as ALTERNATIVE TRADING SYSTEM. See also DEALER MARKET ELECTRONIC COMMUNICATIONS NETWORK, HYBRID ELECTRONIC COMMUNICATIONS NETWORK, REGULATED ELECTRONIC COMMUNICATIONS NETWORK.