examinations worldwide. Cram school culture Singapore, like its neighbors in East Asia, is well known for its cram schools, and literally meaning "make-up class" or "catch-up class" or to learn more advanced classes. Most students from all races attend some sort of cram school, whether it be mathematics, computer skills, other foreign languages, or exam preparation. This is perpetuated by a meritocratic culture that measures merit through testing, with entrance into college, graduate school, and government service decided entirely on testing. This has also led to a remarkable respect for degrees for universities in the country, such as from the National University of Singapore (NUS) or Nanyang Technological University (NTU), which are widely regarded worldwide. As such, universities such as NUS and NTU are also consistently ranked within the top 20 universities in the world and is considered to be the best universities in the Asia-Pacific by the QS World University rankings. National defence Singapore invokes a "whole-of-society national defence concept" called Total Defence. In 1967, conscription or National Service (NS) was officially adopted by the government for the Singapore Armed Forces (SAF), making it compulsory for all male citizens and permanent residents who have reached the age of 18 unless medically exempt. The Singapore government felt that it was necessary to build a substantial military force to defend itself in the face of hostile neighbouring countries, and at the time it only had about 1,000 regular soldiers. It also explained that countries such as Switzerland and South Korea also practices conscription for similar reasons. Furthermore, its rationale was based upon various factors. Firstly, because Singapore has a population of only about 5.5 million, an army solely of regulars would not be practical to defend the country. Secondly, the idea of National Service is supposed to support racial harmony among the races living in the country, which mostly consists of Chinese, Malay and Indian communities. In general, conscription in Singapore continues to show strong support among Singaporeans. Peace and progress The concepts of democracy, peace, progress, justice and equality are enshrined as stars in the Singapore national flag. Furthermore, Singapore has been consistently ranked as one of the top 10 in the world and the highest in Asia on the Global Peace Index. Racial harmony Singapore is a secular country. The main religions in Singapore are Buddhism, Christianity, Islam, Taoism, and Hinduism. Respect for different religions and personal beliefs is