Cons pair
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A cons pair or cell is a data structure from the Lisp programming language, used to couple two values together. The first value in the cons pair is called the car, and the second value is the cdr.
The names "car" and "cdr" have their origins in the assembly code for the IBM 704 computer, where they stood for "contents of the address register" and "contents of the decrement register" respectively.
List links in Lisp (or its daughter, Scheme) are commonly represented using cons'es in which the cdr is a new cons pair.