Teaching English as a second (TESL) or foreign language (TEFL) and teaching English to speakers of other languages (TESOL) are terms that refer to teaching English to students whose first language is not English. The terms TEFL, TESL, and TESOL distinguish between a class's location and student population, and have become problematic due to their lack of clarity. TEFL refers to English-language programs conducted in countries where English is not the primary language, and may be taught at a language school or by a tutor. For some jobs, the minimum TEFL requirement is a 100-hour course; the 120-hour course is recommended, however, since it may lead to higher-paid teaching positions.^{[unreliable source?]} TEFL teachers may be native or non-native speakers of English.

TESL and TESOL include English-language programs conducted in English-speaking countries. These classes often serve populations who have immigrated, temporarily or permanently, or whose families speak another language at home. TESL is considered an outdated term, because students may speak more than one language before they study English. TESOL is an umbrella term that includes TEFL and TESL programs, and is widely accepted in the field of English-language teaching.

Students who are learning English in their home country, typically in a school, are EFL (English as a foreign language) students.

Teaching English as a second language (TESL) refers to teaching English to students whose first language is not English. The teaching profession has used different names for TEFL and TESL; the generic "teaching English to speakers of other languages" (TESOL) is increasingly used, which covers TESL and TEFL as an umbrella term. Both native and non-native speakers train to be English-language teachers. To teach English as a second language to English-language learners (ELLs), passing a written and oral test in English to demonstrate proficiency is recommended but not always required. In California, there is an achievement gap between native and non-native English speakers. English language learners in secondary schools tend to get lower scores in Standard English tests for English Language Arts compared to their peers who are more proficient in English. Combining teaching with traveling is called TEFL tourism.

Communicative language teaching (CLT) emphasizes interaction as the means and goal of learning a language. Despite criticism, it continues to be popular in Japan, Taiwan, and Europe. The Central Board of Secondary Education (CBSE) of India has also adopted this approach in its affiliated schools in the country.

The task-based language learning approach to CLT has gained ground. Proponents believe that CLT develops and improves speaking, writing, listening, and reading skills, preventing students from listening passively to the teacher without interacting. Dogme is a similar communicative approach that encourages teaching without published textbooks, focusing on conversation by learners and teacher.

Code-switching is a common communication practice where an individual alternates or shifts between different languages or dialects within the context of their environment in a social setting. It has become a prominent strategy teachers have tended to implement inside the classroom to help promote and enhance English learning and development.

An aspect of code-switching, called multimodal code meshing, describes how the use of multiple models of media, such as images, videos, etc. to help to further improve students' mastery of English in texts. With the use of various media models, students go through a process of visual brainstorming, creating a thought process through imagination and forming mental images, when code-switching between English and another language. This allowed students and learners to express creative freedom and a personalized and driven learning experience which translated to greater connections and understandings to English from a learner's native language.