Background
Tae Kwon Do has a fascinating background that most practitioners often miss. It was a rebirth of Korean martial arts in order to reach more citizens of the world with the ideology of "Benefiting All Mankind" in mind.
Revolving around General Hong Hi Choi, various Korean martial art masters woke up into the dawn of Tae Kwon Do era in the 1940s. It was the era of independence as well as the era of regaining their lost treasures. Starting from oppressed, torn, and scattered martial art expertise, they rebuilt the body of Tae Kwon Do.
During its rebuilding process, many biomechanical principles of Tae Kkyon, spirit of Silla's Hwarang (empowered by King Jinheung in 6th century) Warriors, and possibly other traditional martial arts such as Subak including both tribal and monks' practices were incorporated to give a birth to a true Action Philosophy that was later named Tae Kwon Do.
In 1955, General Choi (and other members of council) officially named this art "Tae Kwon Do" with intent to keep the basic spiritual aspects and biomechanical principles for further development.
In the 1970s, South Korea President Chung Hee Park (former General) politically empowered Tae Kwon Do and put an intangible seal on the ideology of "Benefiting All Mankind" through its globalization.
Tae Kwon Do truly distinguishes itself from other traditional martial arts by specializing in empty handed and straight lined movements while simultaneously applying speed-over-power, agility-over-stability, and dynamic distance control principles.
Furthermore, these physical principles were successfully combined with its unique rebuilding themes of the unity in diversity, indomitable spirit in common mind, new within old, and benefiting all mankind.
Lastly, the military mentalities of its rebuilding era and Three Kingdom era (Goguryeo, Silla, and Baekje) greatly influenced its mental and spiritual codes solidifying the importance of loyalty, honor, and indomitable spirit on every Taekwondoist's life-long journey.
Philosophy
The words, Tae, Kwon, and Do can be literally translated to Kicking with Foot, Striking with Fist, and Way respectively. However, it is the inner meaning of the combined words that defines what Taekwondo truly is.
It is a life-long journey of attaining indomitable spirit through physical and mental exercises. The mental picture of the sentence above is that one is on a path at the present moment making various statements through one's physical movements to rise above the past, cultivate one's mindset for the future, and prepare oneself with serenity for both success and failure in life.
In other words, Taekwondo forms, sparring, breaking, breathing control, mental visualization exercise, and other important training curriculums are simply a means to attaining indomitable spirit. Taekwondoists may bow down and kneel a hundred times, but they will never give up improving themselves and their spirits will not cease to exist by any worldly means.
In advanced Taekwondo training, the indomitable spirit can be viewed as a renewed spirit attained through physical and mental exercises simultaneously. When the enlightened views on "self" are attained through the advanced training, the renewed spirit will be less likely influenced by any ill-posed ideas or conditions. Hence, the renewed spirit becomes indomitable in the end. The beginning of enlightenment truly starts within. Note that the advance section describes a general practice of the spritual unity of body and mind.
Founding Taekwondoists had to first deal with many different schools of thoughts and philosophies. Fortunately they were able to find unity in diversity by projecting a single vision "Our Taekwondo." Second, they established a tangible baseline from old tradition to strengthen its future. Third, they relentlessly worked toward achieving the goal of "Benefiting All Mankind" as action philosophers.
In other words, true Taekwondoists are action philosophers who practically carry out the detailed plans to turn the ideas into reality.
There are countless Taekowndo practitioners around the globe who are affiliated with ITF, WTF, ATA, or other unions. Regardless of their affiliations and origins, they are simply Taekwondoists. From the humble beginning as in planting a small tree in stormy weather, Taekwondoists grew strong to form a great forest that has a thousand giant trees having their roots tied together underneath the ground.
In summary, Taekwondoists strive to attain indomitable spirit so that they may benefit all mankind.
Notes on Hwarang:
Most people and their migration in Korean peninsula were generally influenced by shamanism (folk religion) up until the late 4th century. Just like other kingdoms in Korean peninsula, Silla's kingship and royal families went through various changes including the role of centural government and official titles of King (Geoseogan -> Chachaung -> Isageum -> Maripgan -> Wang) from its establishment (57 BC) to the unification of the peninsula (668 AD). However, the ideology of Benefiting All Mankind and the philosophy of the spiritual unity of body and mind have survived throughout the history and risen above the treacherous political struggles.
Due to the lack of original Hwarang manuscripts, it may be unclear as to what Hwarang literally means (e.g., Hwa-Shin: fire God, Hwa-Ro: furnace, Hwa-Sal: arrow, Hwa-Won: flower shop, Hwa-Sil: drawing studio, Hwa-Baek: royal council, Hwa: heavenly flower represented with earthly feathers, etc.). However, elite young men were chosen and trained in martial arts and various scholastic subjects according to various historical texts and archaeological artifacts, and they were called Hwarang. At least from the human, as opposed to the omniscient, perspective, this was done to groom future leaders who would strengthen the nation and turn the ideology into reality by looking forward thousands of years.
Note that some modern scholars believe that Hwarang (or its predecessors) had practiced Poong Ryu Do (the way of the flow of wind: traditional action philosophy comprising of art, culture, divine ritual, and body-mind cultivation in universal harmony; ideology of universal energy flow in both physical and spiritual realms) prior to the religious, political, and military empowerment.
One of well-trained Hwarang warriors was General Kim Yu-sin (595-673 AD) who fulfilled his duties to protect Queen Seondeok of Silla and unify Korean peninsula as Gukseon. To modern Taekwondo practitioners around the globe, Gukseon Kim Yu-sin's words, "It is not who is strong that survives, but who survives is the strong," shall echo through space and time.