In Java, the Java API for XML Processing (JAXP) provides a set of interfaces and classes that allow you to work with XML documents in a platform-independent manner. JAXP provides support for both parsing and generating XML documents, as well as for transforming documents using XSLT stylesheets.

JAXP includes several sub-APIs, each of which provides a different level of abstraction for working with XML:

1. The Document Object Model (DOM) API provides a way to represent an XML document as a tree of nodes, which can be manipulated programmatically.

2. The Simple API for XML (SAX) API provides a streaming-based approach for parsing and processing XML documents.

3. The Streaming API for XML (StAX) API provides a low-level, pull-based approach for parsing and processing XML documents.

4. The XML Binding (JAXB) API provides a way to map Java objects to XML documents and vice versa.

5. The XPath API provides a way to navigate and query an XML document using XPath expressions.

6. The XSLT API provides a way to transform an XML document using an XSLT stylesheet.

JAXP is included as part of the Java Standard Edition (SE) and is therefore available on all Java platforms. It is a powerful and flexible API for working with XML documents, but it can also be relatively complex and memory-intensive for large documents. Depending on the requirements of your application, you may want to consider other XML processing libraries or frameworks, such as JAXB or Apache XMLBeans.