Backus-Naur Form, a “metasyntax notation for context-free grammars”.

The Earley parser is a chart parser that uses dynamic programming. It is an early (no pun intended; the first?^{citation needed}) example of a parser that can parse all context-free languages, not just subsets in which ambiguity can be resolved with some constant lookahead.

Extended Backus-Naur Form, an extension of basic Backus-Naur form grammars, often to make authoring easier.

A fully general LL parser. An LL parser is one that operates from left-to-right using the leftmost derivation. Informally, GLL is an LL parser that is capable of resolving ambiguous parsers.

The Java virtual machine, the platform on which languages like Java, Scala, Groovy, Kotlin, and Clojure operate.

The X-stack is an informal way of referring to the collection of XML-related technologies used to build applications: XML, XSLT, XQuery, XProc, XForms, RESTXQ, etc.