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Now the core: Clojure's fundamental data structures and the simple syntax that makes it so expressive.

Clojure is built from S-expressions: parenthesized lists where the first element is a function and the rest are its arguments. Everything is an expression.

The basic literals are numbers, double-quoted strings, and the booleans true/false — each evaluates to itself.

A list in parentheses is treated as a function call by default. To make it data, quote it with an apostrophe like '(1 2 3).

Vectors use square brackets and are zero-indexed. Prefer them over lists when you want fast positional access.

Maps store key-value pairs in curly braces, usually with keyword keys like :name — perfect for structured data.

A set in #{} holds unique, unordered items and silently drops duplicates. Ideal for fast membership checks.

Keywords start with a colon, like :email. They are self-evaluating constants, used everywhere as efficient map keys.

A symbol is a name that refers to a variable or function. Clojure resolves it on evaluation; quote it ('sym) to treat it as data.

Which of the following Clojure data structures is best suited for storing a collection of unique items where order doesn't matter?

Recap: S-expressions drive the syntax, with lists, vectors, maps, sets, keywords, and symbols as your core building blocks.