ESL books provide the basics for individuals to learn English grammar, fluency, vocabulary, and helpful insights that teachers can use to facilitate teaching, whether for the children or adults in more classroom settings. Despite most of these books being used by teachers due to their technicality in the English language, some can also be used by students for reference and other learning resources. For example, students from non-native English-speaking countries coming to the United States and Canada for an extended duration are taught using these books and teaching English overseas as a second language for ESL students.