The key concept here is "bursts". Bursts refer to the sudden increase in the frequency of a particular word or phrase within a text. These bursts of words are often indicative of the main topics or themes being discussed in the text. By identifying these bursts, we can extract keywords that encapsulate the central ideas of the text. Keywords, in turn, play a crucial role in natural language processing (NLP) tasks such as text summarization, information retrieval, and machine learning algorithms for text analysis.