Nowadays, electronic documents are the main resource to store a huge amount of information on several fields. Usually, this information is in the form of text that implies a big effort to extract the patterns of interest. Text mining aims to manage and extract knowledge from unstructured documents. In the last years, several techniques have been addressed to recognize entities and concepts, categorize documents, analyze the opinions and the sentiments of the writers, and extract the information of interest for the readers. Summarization approaches are suitable for identifying relevant sentences that describe the main concepts presented in the documents and provide to the readers only a useful subset of information according to the topic of the document set or to the major user interests. In this book we discuss the state-of-art of summarization research field and we present some new summarization techniques.