Text-mining programs go further, categorizing information, making links between otherwise unconnected documents and providing visual maps via What is Text Mining? | Information Space.
Text mining, or the indexing of content, is important because it allows us to make sense and extract meaning out of large amounts of data. Text-mining is an activity also related to data curation, the semantic web, big data and bioinformatics. Its becoming more popular as a way to conduct research and information retrieval within databases.
Here is an informative presentation called The Library as Dataset: Text Mining at Million-Book Scale from Yale University, which discusses a text mining method, digital humanities and libraries.
Here is an article with an information science perspective called Text Mining and Information Retrieval, Canadian Journal of Information and Library Science, 2011, 35(3), pp. 223-227, if you have access to scholarly databases.