Shuffle

Shuffle is a term with multiple related meanings in everyday language. As a verb, it can mean to slide the feet along a surface without fully lifting them, or to mix or rearrange items in a less-than-rigid way. As a noun, it can refer to the action itself or to the resulting arrangement, such as a deck of cards that has been mixed.

In card dealing, shuffling aims to randomize the order of a deck to prevent predictability. Common methods include the overhand shuffle, the riffle (or dovetail) shuffle, the Hindu shuffle, and pile shuffles. The riffle shuffle, where the deck is split and the halves interleave, is widely used and has several variations such as the out-shuffle and in-shuffle. In practice, several consecutive shuffles are usually required to approach randomness; popular guidance often cites about seven riffle shuffles to approximate a uniform random order. In formal contexts, guaranteed randomization may be achieved with a shuffle algorithm or a trusted random number generator.

Outside card games, shuffle has related meanings in computing and media. In computing, a shuffle refers to generating a random permutation of a list using algorithms such as Fisher–Yates (Knuth shuffle). In music playback, the shuffle mode randomizes the order of tracks, sometimes with options to avoid repeats or to constrain playback to a subset. In dance, the term describes a family of footwork styles, including the Melbourne shuffle, characterized by rapid sliding steps and rhythmic movement in electronic dance music contexts.