A matryoshka doll (Russian: матрёшка; IPA: [mɐˈtrʲɵʂkə], matrëška), also known as a Russian nesting doll, or Russian doll, are used metaphorically, as a design paradigm, known as the "matryoshka principle" or "nested doll principle". It denotes a recognizable relationship of "object-within-similar-object" that appears in the design of many other natural and crafted objects. Examples of this use include the matrioshka brain and the Matroska media-container format.

The onion metaphor is of similar character. If the outer layer is peeled off an onion, a similar onion exists within. This structure is employed by designers in applications such as the layering of clothes or the design of tables, where a smaller table nests within a larger table, and a smaller one within that.

The Matroska (MKV) multimedia container format derives its name from Matryoshka, alluding to the container being able to hold many different types of content streams.
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