How does the belt ranking system work in the Korean martial art of Hapkido?

You're thinking of Taekwondo:
Tae = Foot
Kwon = Fist
Do = the way, or art of...

In order to move from white belt to white belt with yellow stripe in Hapkido, the student must do the following:

• Roll back and forward
• Perform break-falls
• Perform defenses against wrist grabs and hand attacks
• Perform "breaking" (Kyuk Pha)- 1 inch board with kick and 1 inch board with hand.
• Learn the history of Hapikdo an IHF
• Write a 2-page essay

The first martial art to use the belt ranking system is the Japanese Judo.

In the Israeli martial arts of Krav Maga, the ranking system is as followed from low to high: yellow, orange, green, blue, brown, and black.

Absolutely. In different forms of martial arts, there are different levels for practitioners with black belt. For example, in Karate and Judo, there are 10 different ranks (dan) for someone with a black belt. So there's always room for progress.

Many styles of martial arts use a belt ranking system; however they may not all equate to the same skill level. Here are a few styles and their ranking order:

Karate - white, yellow, orange, green, blue, brown and black

Tae Kwon Do - white, yellow, green, blue, red and black

Judo - only uses white, brown, red and black

Kung Fu - no established belt ranking system

The person to originate the use of a belt ranking system was Kano Jigoro, the founder of Judo, in the 1880's.

The color of the belt signifies the amount of knowledge you have obtained. Wearing a white/yellow belt means you know some basics - in terms of blocks, kicks and punches. You will reach a better understanding of martial arts techniques in further levels like green, blue and purple. Brown and black level students have applied learned techniques.

The ranks of the karate belts are in this order: White, Yellow, Green, Purple, Brown, Black, Red /white

The idea was firstintroduced in Europe in 1935 to encourage people to continue training inmartial arts and to award the trainee certain levels of achievements.