Unstructured data are non- structured data (see also "Structured data”). People are using unstructured data every day; examples of unstructured data are emails, webpages, documents, images and spreadsheets.This kind of data does not have a structured format, it has no conceptual or data type definition.
Human intervention is needed to make this unstructured data ready for technological processing. Within a BI context unstructured data is more and more considered to be a potential source for the data warehouse and thus also for being manipulated in the ETL layer.