The document proposes a system for understanding short texts by exploiting semantic knowledge from external knowledge bases and web corpora. It discusses challenges in analyzing short texts using traditional NLP methods due to their ambiguous and non-standard language. The system addresses this by harvesting semantic knowledge and applying knowledge-intensive approaches to tasks like segmentation, POS tagging and concept labeling to better understand semantics. An evaluation shows these knowledge-based methods are effective and efficient for short text understanding.