Rapid changes in the 21st century world also affect and change the functions of schools and teachers. Schools, teachers and even printed books are no longer the only source of information. We are in a period where learning is not limited only to school life, but we can access information through different channels throughout life. Schools have become life itself, not institutions that prepare individuals for life. This transformation adds differences to our expectations, perceptions and values as a society. Although the function of school and teaching has changed, it has had to become an institution and profession that can keep up with the changes that constantly renew themselves. Teachers' ability to follow the changes in their field, adopt an interdisciplinary approach, and have lifelong learning as their philosophy increases the importance of teachers' professional development. Because; The success of the education system in a country depends on the qualifications of the teachers who will run this system. Especially the change in the qualifications and skills sought in the transition from the 20th century to the 21st century affects education and the knowledge and skills required in teachers, which are components of education. While pre-service education faculties organize their programs according to teacher competencies, it is of particular importance in today's world that in-service or professional development programs are organized according to 21st century skills and are need-oriented. In this section, the professional development of teachers based on 21st Century skills is emphasized.