Chunking is a powerful cognitive technique that improves short-term memory retention by organizing information into smaller, more manageable units. The brain, limited by working memory capacity, can more easily process and store information when it is divided into "chunks" rather than presented as discrete, unrelated elements. Chunking is especially useful when dealing with large amounts of information, such as numerical sequences, words, or complex ideas.

The principle behind chunking is rooted in cognitive load theory, which posits that working memory can only handle a limited amount of information at once. Chunking reduces this cognitive load by combining smaller elements into a single meaningful unit. For instance, a long sequence like a 16-digit credit card number "1234567890123456" is more easily remembered when divided into smaller groups of "1234-5678-9012-3456". This approach eases the memory load by enabling the brain to treat each set of grouped digits as one cohesive unit: chunks.

George A. Miller's influential theory, often called the "7 ± 2" rule, provides a quantitative framework for understanding chunking's effectiveness. According to Miller, the average human working memory can hold approximately five to nine chunks of information at once. Chunking maximizes this capacity by allowing the brain to encode and recall more information within the limited working memory space. However, recent research suggests that working memory capacity might often be closer to 4 ± 1 chunks, depending on various factors like the complexity of chunks and individual differences in cognitive capacity.

Chunking is also an advantage in language acquisition. Learners commonly group related vocabulary into categories, such as animals or fruits, to facilitate easier recall. Learners can more efficiently retain and retrieve information by associating individual words with broader categories, highlighting chunking's broader cognitive benefits.