Mining structures for semantics
Xin Luna Dong, Jayant Madhavan, Alon Y. Halevy · ACM SIGKDD Explorations Newsletter · 2004
Online data is available in two avors: unstructured data that resides as free text in HTML pages, and structured data that resides in databases and knowledge bases. Unstructured data is easily accessed as human-readable text on a browser, while structured data is hidden behind web query interfaces (web forms), web services, and custom database APIs. Access to this data, popularly referred to as the hidden web, entails submitting correctly completed web forms or writing code to access web services using protocols such as SOAP.