South Korea came to a grinding halt on Thursday as 650,700 high

South Korea came to a grinding halt on Thursday as 650,700 high school seniors prepared to take the most important exam of their lives: the college entry exam.

Securing a high grade on your College Scholastic Ability Test (CSAT) practically guarantees access to one of Korea’s top three universities, and a job with the civil service or one of South Korea’s chaebols – business conglomerates – Samsung, Hyundai and Daewoo.

Trading on South Korea’s stock market was halted for an hour, opening at 10am, instead of 9am, while planes were prevented from taking off or landing for 40 minutes and the military stopped conducting drills, to reduce noise as students took their exams at over 1,250 test centers, according to media reports.

The top three universities in South Korea are known as the SKY universities, an acronym devised from the first three letters of their names, referring to Seoul National University, Korea University and Yonsei University. Seoul National is considered the most prestigious.

South Korea’s university tuition fees are the third most expensive out of all the Organization of Economic and Co-operation and Development countries, according to South Korea’s Ministry of Education, Yonhap News Agency reported this week.

Yonhap also reported in May that the nation’s competitive education system had led to suicide being the largest cause of death among young people aged 15-24 years in South Korea, according to Statistics Korea, for the third consecutive year in 2010.

– By CNBC’s Katie Holliday: Follow her on Twitter @hollidaykatie