Unstructured data consists of any dataset that does not have a predefined organizational schema as in the table in the prior section. Spoken words, music, videos, and even books, including this one, would be considered unstructured. This by no means implies that the content doesn’t have organization. Indeed, a book has a table of contents, chapters, subchapters, and an index--in that sense, it follows a definite organization.

However, it would be futile to represent every word and sentence as being part of a strict set of rules. A sentence can consist of words, numbers, punctuation marks, and so on and does not have a predefined data type as spreadsheets do. To be structured, the book would need to have an exact set of characteristics in every sentence, which would be both unreasonable and impractical.

Unstructured data can be stored in various formats. They can be Blobs or, in the case of textual data, freeform text held in a data storage medium. For textual data, technologies such as Lucene/Solr, Elasticsearch, and others are generally used to query, index, and other operations.