Which of the following is NOT a programming language discussed in this segment? - Fluid Application Language - Cascading Style Sheets - Structured Query Language - Extensible Markup Language

In the provided list, "Cascading Style Sheets" (CSS) is NOT a programming language. It is a style sheet language used for describing the presentation of a document written in HTML or XML (including various XML languages like SVG or XHTML). CSS describes how elements should be rendered on screen, on paper, in speech, or on other media.

Extra: Programming languages are used to create programs that can perform different kinds of operations on a computer or other devices. They usually allow the programmer to write code that is converted into machine language and then executed by the computer to perform specific tasks. Let's briefly look at the other terms mentioned:

- Fluid Application Language: This does not appear to be a well-known or widely recognized programming language and could potentially be a fictitious name or a very specialized domain-specific language not discussed broadly in programming communities.

- Structured Query Language (SQL): This is a real programming language but is specifically designed for managing and querying relational databases. It is not generally used for developing standalone applications, but rather for data manipulation and query within databases.

- Extensible Markup Language (XML): Although not a programming language, XML is a markup language very similar to HTML. It is used to define rules for encoding documents in a format that is both human-readable and machine-readable. It is primarily used for the storage and transport of data.

Remember that in the world of computer science, the term "programming language" is reserved for languages that provide structures like loops, conditionals, and data types to perform computation and manipulation of data. In contrast, a "markup language" or a "stylesheet language" serves different purposes and does not include these computational capabilities.