Teachers' Day is a special day for the appreciation of teachers, and may include celebrations to honor them for their special contributions in a particular field area, or the community in general.
The idea of celebrating Teachers' Day took root in many countries during the 19th century; in most cases, they celebrate a local educator or an important milestone in education (for example, Argentina has commemorated Domingo Faustino Sarmiento's death on 11 September) since 1915 while India traditionally celebrates Guru Purnima, an Indian and Nepalese festival dedicated to spiritual and academic teachers which is celebrated on the full moon day (Purnima) in the Hindu month of Ashadha (June–July) as it is known in the Hindu calendar of India and Nepal. The birthday of Dr. Sarvepalli Radhakrishnan (5 September) is also celebrated as Teacher's Day in India since 1962. This is the primary reason why countries celebrate this day on different dates, unlike many other International Days.
Read More: https://en.wikipedia.org/wiki/List_of_Teachers%27_Days