JDOM (Java Document Object Model) is a Java-based library used for working with XML documents. It provides a way to traverse, modify and create XML documents using a high-level API. It allows developers to access and manipulate data in XML files with ease, making it a popular tool for developing XML-based applications. JDOM offers a straightforward and easy-to-use model, making it easy for developers to work with complex XML files from within their Java applications.