History
Gi Cho Hyung Forms are basic movements for new students.   Gi Cho means Basic
Hyung means Form.

Gi Cho Hyung Il Boo = Basic Form 1
Gi Cho Hyung Ea Boo = Basic Form 2
Gi Cho Hyung Sam Boo = Basic Form 3

Pyung Ahn Hyung (loosely translated means balance and comfort)
The five Pyung Ahn Hyungs were originally called Je Nam Hyung.  It was devised
approximately 130 years ago by separating Je Nam Hyung into five components.  
Pyung Ahn Hyung symbolises the Turtle.  The Turtle is believed to hold the secret of
heaven and earth within its body. The Turtle Forms are to increase balance and
comfort.

Pyung Ahn Cho Dan Hyung  1st
Pyung Ahn Ea Dan Hyung    2nd
Pyung Ahn Sam Dan Hyung 3rd
Pyung Ahn Sa Dan Hyung    4th
Pyung Ahn Oh Dan Hyung    5th

Ba Sa Hee Hyung (Quick, Fast)
Ba Sa Hee Hyung was devised approximately 450 years ago.  It is based on the art of
boxing and has undergone many changes while evolving into its present form.  It was
practised by the Buddhist monks at the So Lim Sa Temple situated in the Ha Nam
region of China, and consists of careful selected moves from the So Lim Sa techniques,
which are executed with the effective use of force and speed. Ba Sa Hee Hyung
symbolises the Cobra, quick and fast.

Chil Sung Hyung: Seven Stars of the Plough (Seven Bright Stars in the constellation
Ursa Major)
The Chil Sung Hyung was devised by Grand Master Hwand Kee in the latter half of the
1980's.  It is so-called because Grand Master Hwang Kee's mother was said to have
dreamt about the seven stars of the Plough prior to conceiving Hwang Kee. It contains
large number of moves, many of which are found only within this Hyung.  Chil Sung
Hyung symbolises the Stars.  

Chil Sung Il Ro Hyung
Chil Sung Ee Ro Hyung
Chil Sung Sam Ro Hyung

Naihanji Hyung
The Naihanji Hyung was devised 950 years ago, during the era of the Song Dynasty,
by the founder of the Kang Woo Ryu school of martial arts.  It is characterised by a
horse riding posture in all movements, with both feet placed toe-in.  Naihanji Hyung
symbolises the Horse.  

Naihanji Cho Dan Hyung
Naihanji Ea Dan Hyung
Naihanji Sam Dan Hyung

Ship Soo (Jin Thwe) Hyung
Also known as Jit Dae, this Hyung originates from the Ha Book region of China.  The
originator is unknown.  It is characterised by only a small number of moves, practised in
a slow dignified manner with concentrated power.  Ship Soo Hyung is particularly
suitable for people with a large physique, or holders of the 4th or 5th Dan and
symbolises the Bear.  

Jin Do Hyung
Jin Do Hyung was originally known as Jin Dwe and was developed in the Ha Nam region
of China about 300 years ago.  The originator is unknown.  It belongs to the So Lim
School of Martial Arts, and consists of many technically demanding and rapid
movements.  Jin Do Hyung symbolises the Crane.

Kong San Goon Hyung
This Hyung was devised by Ggung and Ssang Gween who lived in the Ha Nam region
of China, and contains many fascinating, varied and effective movements.  The
movements portray the repelling of enemies attacking from four directions.  It is
regarded by many as the Hyung of all Hyungs and Symbolises the Eagle.

Ro Hai Hyung
Ro ai Hyung belongs to the So Lm school of martial arts.  Its originator is unknown.

Resources:
Book: Tang Soo Do The ultimate guide to the Korean Martial Arts by Grand Master
Kang Uk Lee
This is a quick overview of
the History of Korean
Forms.