OPT (Optional Practical Training) refers to a kind of internship employment permit that American international students can apply for after completing their studies. Students can apply for 12 months of OPT (1 year), or students studying in STEM (science, technology, engineering, mathematics) fields can apply for an additional 24 months of STEM OPT (total of 3 years). OPT allows students to find internships or jobs related to their majors in the United States, gain practical experience and improve career skills. OPT is an important opportunity for international students to obtain employment in the United States after graduation, helping them gain practical work experience and take the first step in career development.