1. A method of generating Frequently Asked Questions (FAQ) data from Community-based Question Answering (CQA) data, the method comprising: receiving a plurality of data sources and a topic having one or more themes, wherein each data source has data associated with one or more topics; generating a thematic hierarchy of the plurality of data sources; classifying a plurality of CQA data into one or more themes based on the thematic hierarchy, where the CQA data containing a plurality of question-answer pairs; selecting a plurality of question-answer pairs from the CQA data based on the classification, the selecting comprising: for each theme of the CQA data, grouping a plurality of CQA data into a plurality of clusters, wherein the CQA data in a cluster share one or more features associated with the theme, and a cluster of CQA data has a centroid representing the theme of the cluster; and generating FAQ data using the selected question-answer pairs of the CQA data.