A system, methods, and user interface for automatically extracting important terms from a document content as terms representing the important information in the content, and using the extracted term or terms to label the document, either as a tag or a summary or category, or for renaming the document. Methods for determining the terms as important include content analysis methods based on grammatical, semantic, contextual, positional, frequency, and other attributes associated with the terms. Documents can include any type of document containing text, including personal or company documents, Web pages, emails, reviews and comments, etc. In some embodiments, a document can also be a collection of documents.