Users can submit URLs for indexing and there is no criteria used in the selection process. The entire web page is indexed. No controlled vocabulary is applied. The only searching available is natural language. The default search option is Boolean AND search which can be frustrating because most Web search engines default to a Boolean OR operator.
Open text is a good search engine for the advanced searcher.
The relevanced-ranked citations show the title, address, size, relevancy score, and an abstract from the page. The abstract is created by the robots upon indexing the page. They look at the first one hundred words on the page, discard the HTML, and the rest becomes the abstract. One unique feature is that users can look at the places on the page where the search term was found in a KWIC index. It was started by two graduate students at Stanford.