Classified as a Ural-Altaic language, Korean is currently spoken by nearly 78 million people worldwide. In addition to being the primary language in both North and South Korea, Korean is also spoken in parts of China, Japan, Brazil and Australia.
Like many languages, the history of Korean can be divided into three distinct eras: Old Korean, Middle Korean and Modern Korean.
The era of Old Korean spans a period known as the Three Kingdoms of Korea, which began with the Common Era and ended in about 1000 CE. During the Three Kingdoms, the Korean peninsula was divided into three distinct regions: * Goguryeo, which spanned the northern and middle area of the Korean peninsula; * Baekje, located in the southwestern region; * Silla, in the southeastern zone.

This regional divide soon triggered the development of Korean dialects, as regional differences in culture nuanced Old Korean. While the Korean language was evolving, the Silla dialect was adopted as the standard form of the language.
This period of time was also marked by the using Chinese ideograms, so-called Hanja. Hanja is the Korean name for Chinese characters (hanzi).[1] More specifically, it refers to those Chinese characters borrowed from Chinese and incorporated into the Korean language with Korean pronunciation.

Middle Korean (중세국어, 中世國語) corresponds to Korean spoken from the 10th to 16th centuries, or from the era of Goryeo to the middle of Joseon.
The language standard of this period is based on the dialect of Gaeseong because the new Goryeo Dynasty moved its capital city to the northern area of the Korean Peninsula.
The main innovation of that period was the creation of the Hunminjeongeum. Hunminjeongeum translated as The Proper Sounds for the Instruction of the People. The project was completed in late December 1443 or January 1444, and promulgated in September or October 1446 by Sejong the Great, the 4th king of the Joseon Dynasty.
Hunminjeongeum was an entirely new and native script for the Korean language and people. The script was initially named after the publication, but later came to be known as Hangul. It was created so that the common people illiterate in hanja could accurately and easily read and write the Korean language. Its supposed publication date, October 9, is now the "Hangul Day" in South Korea.
However, educated people prefered to use Hanja instead of Hangul.

Modern Korean (근대국어, 近代國語) corresponds to Korean spoken from the 17th century onward.
History of the Korean language was largely marked by dialectal evolution, as well as Chinese and Japanese influences. During the Japanese invasion Korean Language was in process of suppressing. Most of Korean words was changed into Japanese. Nevertheless, after becoming independent Korean Language was totally disposed of Japanese words.
Over the decades following the Korean War and the division of Korea, North–South differences in the Korean language have developed, including variances in pronunciation, verb inflection and vocabulary.
Modern Korean – arising with the dawn of the 20th century – has primarily been shaped by English influences, as interactions with the U.S. ushered in new vocabulary.
Konglish is the use of English words or words derived from English words in a Korean context. Konglish terms, having initially been taken from the English language, are made from a combination of Korean and/or English words (such as Officetel 오피스텔 Office + Hotel) which are not used in English-speaking countries. but native English speakers usually don't understand Konglish,

Koreans use the direct transliteration of "fighting" as the Konglish term hwaiting or paiting (화이팅/파이팅) to cheer someone on, meaning "don't give up".

Today, the spoken Korean language is still characterized by various dialects (one primary dialect in North Korea and five different dialects in South Korea). Unlike Chinese, Modern Korean dialects are mutually intelligible.