So Barnetmill asked about this on Warriortalk. The concept of Kata is universal. You see it in many martial disciplines (I hate the word "art"). Here is the concept applied in a very simple and basic US Soldiers...

Its a way to codify, memorize, and repeat movement patterns extensively in a memorable and dynamic manner. Doing five kicks, while moving in a kata has more application and is more interesting than simply standing there and doing five kicks. Moving on.

As I said in the video...just as dry practice is not an end to itself and is training for live fire, kata are for fighting. The modern understanding of kata by the martial gymnasts is that kata is an end onto itself and exists as a gymnastic demonstration of artistic and athletic prowess.

The kata as we know them today all originated in Okinawa. Anything originally taught in Okinawa, then to Japan, and then to Korea, has roots in Chinese fighting systems. I studied Kyokushin Karate, and then a couple of other systems...then a non-Taekwondo Korean system...and with minor variations and names...all the kata were pretty much the same.  That is no shows lineage.  To really get to the bottom of this you need to leave nationalism behind and Asians are terrible about this.  Everyone claims what they teach was invented by their own culture and never give credit where its due.  Koreans sneer at the Japanese and both despise the Chinese and as far as the Okinawans...all of them look down on the Okinawans.
But the funny thing is that if you do a Korean version of Kushanku, although they call it Kong Sang Koon, it looks remarkably the same as the Japanese Kanku Dai...and that one looks very similar to the Okinawan Kusanku. Wow!

Incidentally - there were three major schools or groups of schools on Okinawa. These were the Shuri, Naha, and Tomari. The kata I showed in the video is Bassai (alternatively known as Passai, Bassai Dai, Pal-sek, and Patsai) is Shuri and Tomari-based. I practice kata from all three schools as they each have attributes worthy of having. If there is interest, perhaps Brent Yamamoto and I will do a few here.

The original Kata as taught in Okinawa and in fight-centric schools outside Okinawa (Goju-Ryu as one example, and the Kyokushin that developed from it) featured lots of strong hand techniques, tight tall stances to allow for movement changes, and low kicking. It was preparatory for hand to hand combat.

When Itosu (Okinawa) and Funakoshi (Japan) introduced Karate into the respective school systems of each nation, they did so largely as a physical fitness matter, not a fighting matter. And the forced transition from Jutsu (fight-focused) to Do (sport-focused) by the Japanese government forced the combat system to develop into areas of sport, self-perfection, etc. The low stances, the high kicks, the military organization, were all added at this point and absent in original karate. Also added at this point were the training uniform (Gi, Do Gi, Doebok, or whathaveyou) and belt rankings...AND...the inevitable competitions...and the techniques designed to win them.

Original Okinawan Karate was taught informally in street clothes, no belts were given, and competition was non-existent. Here is a short clip of Yamaguchi, one of the founders and originator of Goju-Ryu. Yamaguchi, incidentally was no theoretical guy as he did well in real fights. Hardly the "flash and spectacle" of a "modern hollywood karate".

And here is Oyama doing the same

To present an analogy closer to home, imagine what we do..."gunfighting".

It is a good name for a martial discipline - GUNFIGHTING.
"It is for killing other men in fights involving firearms primarily, but covers other forms of attack as well. Our discipline (Suarez-Ryu?) encompasses proactive and reactive events, at various distance intervals and includes a hand to hand segment intended to regain the initiative and access the pistol. Primarily a pistol system, we also use rifles and shotguns and SMGs in a similar framework. We have segments teaching fitness and tactics and mental/spiritual aspects dealing with mind set, attitude, warrior ethos, verbal articulation, and other similar matters. Rather than Buddhist or Taoist, our underlying core principles are Christian (although perhaps not the sort of Christian most picture when they picture an American Christian)."
That in a nutshell is our system.

Now imagine you tasked with using that to teach liberal-snowflake middle schoolers to concentrate better, to become agile and fit, and to learn hand eye coordination. Would you include all of the above? Unlikely. That is what Funakoshi and Itosu did.  And much of Real karate was lost as a result.

Korean "Karate" is the same. Modern competitive Tae Kwon Do has as much in common with street combat as foil fencing has with gutter knife fighting...but the roots are basically Okinawan with flashy hallmark kicks added.  There are still fight-based Korean Karate systems.  I was fortunate to have trained in one with Don Baird (a direct student of Young Suh), but such schools are very few.

As a student of combat, whether it is Karate, JuJitsu, or American Pistol Shooting, it is incumbent on you to know the roots of what you study. By knowing where it all came from, and why something was taught a certain way, the all-important "WHY" becomes evident and not only do you gain a greater understanding of things, but you become a better warrior as a result.