The rsearch consists of an introduction, three chapters, a conclusion, a list of used literature and appendices. Vocabulary plays a key role in teaching English. Without sufficient vocabulary, students cannot understand others or express their thoughts. This dissertation presents important issues of recent research and theories on vocabulary, so that teachers can approach vocabulary teaching in a principled manner. It covers the issues of understanding vocabulary, the importance of vocabulary, the results of relevant research, the level of students' vocabulary and effective teaching of...