Phrases are a group of consecutive words within a sentence that can convey a specific meaning. For example, in the sentence Tomorrow is going to be a rainy day the part going to be a rainy day expresses a specific thought. Some of the NLP tasks extract key phrases from sentences for search and retrieval applications. The next smallest unit of text is the word. The common tokenizers split sentences into text based on punctuations like spaces and comma. One of the problems with NLP is ambiguity in the meaning of same words used in different context. We will later see how this is handled well when we discuss word embeddings.