Text is often called an unstructured format. There is a lot of information there, but it is just there; no headings, no required format, loose syntax and other problems prohibit the easy extraction of information from text. The data is also highly connected, with lots of mentions and cross-references—just not in a format that allows us to easily extract it!

We can compare the information stored in a book with that stored in a large database to see the difference. In the book, there are characters, themes, places, and lots of information. However, the book needs to be read and, more importantly, interpreted to gain this information. The database sits on your server with column names and data types. All the information is there and the level of interpretation needed is quite low. Information about the data, such as its type or meaning is called metadata, and text lacks it. A book also contains some metadata in the form of a table of contents and index but the degree...