A meta language is a language used to describe or define other languages. It provides a framework or set of rules to specify the syntax and semantics of a target language. The purpose of a meta language is to facilitate the creation, analysis, and manipulation of programming languages or formal systems. One well-known example of a meta language is the Extended Backus-Naur Form (EBNF). EBNF is commonly used to specify the syntax of programming languages and other formal grammars. It defines a set of symbols and syntax rules using a combination of terminal symbols (such as letters and numbers) and non-terminal symbols (used to define production rules). Another example is XML Schema Definition (XSD), which is used to define the structure, content, and data types in an XML document. XSD allows developers to specify constraints on elements, attributes, and their relationships in an XML file. YAML Ain't Markup Language (YAML) is another meta language that focuses on data serialization. It provides a human-readable format for representing structured data in key-value pairs or lists. YAML allows you to define custom data structures, specify types, and create complex hierarchies. Regular Expressions (regex) are also considered a type of meta language. They provide a concise way to describe patterns in text using special characters, quantifiers, and modifiers. Regular expressions are commonly used for pattern matching, text parsing, and data validation tasks. Apart from these examples, there are various domain-specific meta languages designed for specific purposes such as modeling languages like Unified Modeling Language (UML), query languages like Structured Query Language (SQL), transformation languages like XSLT (Extensible Stylesheet Language Transformations), etc. # Conclusion Overall, meta languages play a crucial role in software development by offering tools and standards for defining the syntax, structure, and behavior of other languages or systems. # References ```dataview Table title as Title, authors as Authors where contains(subject, "meta language") or contains(title, "meta language") or contains(title, "Meta Language") or contains(subject, "Meta Language") or contains(title, "Metalanguage") or contains(title, "Meta language") or contains(title, "Meta-language") ```