Because idioms are omnipresent in the authentic language students are exposed to, to successfully comprehend and produce natural language, learners of a second or foreign language need to possess a good knowledge of idioms and competence in idiom use. This paper examines the approaches to teaching and learning idioms. A discussion of the importance of idioms in language proficiency will first be carried out. Several different definitions of idioms will be presented, and typical characteristics of idioms will be provided. How idioms differ from idiomaticity and proverbs will too be pointed out. In addition, various types of idioms will be identified. Approaches to idiom instruction and strategies for idiom acquisition will be surveyed, respectively. Finally, materials for idioms learning and teaching will be reviewed in order to assist classroom teachers to effectively design idiom lessons as well as to teach idioms in a fun and interesting manner. This paper is of special relevance to foreign and second language classroom practitioners who are interested in developing learners' idiomatic language comprehension and production.