With the rapid growth of mobile device usage, more and more mobile contents offer a great opportunity for mining useful information. However, these contents mostly exist in free-text format in web pages, news feeds, SMS, and Twitter/WeChat messages, posing a significant challenge for information extraction. Natural language processing (NLP) is an important field of computer science, artificial intelligence, and computational linguistics. It is concerned with the interactions between computers and human (natural) language. NLP aims to enable a computer program to process and understand unstructured texts. In the mobile environment, NLP can make apps smarter by automatically analyzing the content, understanding its semantics, and taking appropriate actions on behalf of their users. The state-of-the-art NLP techniques have proven to be useful in dealing with the information overload problem in the mobile environment, e.g., news aggregation and summarization, question answering, information extraction and retrieval, semantic understanding, and personalization.