JBoss AS, or JBoss Application Server, is an open-source application server that implements the Java EE (Enterprise Edition) specifications. It provides a platform for building, deploying, and hosting Java applications, making it easier for developers to create robust and scalable enterprise solutions. Originally developed by JBoss, Inc., JBoss AS is now part of the Red Hat portfolio. It supports various services such as transaction management, messaging, and web services, allowing developers to focus on application logic rather than infrastructure concerns. Its flexibility and community support have made it a popular choice for enterprise-level applications.