Information extraction systems are traditionally implemented as pipeline of special-purpose processing modules targeting the extraction of a particular kind of information.html tag based data are extracting the data usually generated for visualization not for data exchange. Each web page may contain several groups of semi structured data. Each web page is generated by data values to predefined templates page. Manual data extraction from semi supervised web pages is a difficult task. This paper focuses on study of various automatic web data extraction techniques by using html tag based.