Seoul is the capital city of South Korea. It is a very large city, and it is the country’s main centre for business, industry, government, universities, and culture.

Seoul首爾 is the capital city是首都 of South Korea韓國的。It它 is a very large city是一座非常大的城市, and而且 it is the country's main centre它是這個國家主要的中心 for business, industry, government, universities, and culture在商業、工業、政府、大學和文化方面。

In English this is a place name, so it takes a capital S.

In English在英文裡 this is a place name這是一個地名, so所以 it takes a capital S字首S要大寫。

The English spelling comes from Korean 서울, which literally means “capital city.” Older ways of writing Korean in the Latin alphabet — including a French-based spelling by Dallet and the 1959 South Korean school system — used the letters “eo” for the Korean vowel ㅓ. Though actually, English Seoul is older than the romanization South Korea uses today; the newer system just happens to spell this city the same way.

The English spelling英文拼法 comes from Korean 서울來自韓文的서울, which literally means這個字照字面意思是 "capital city."「capital city」。Older ways of writing Korean in the Latin alphabet早期把韓文寫成拉丁字母的方式 — including a French-based spelling by Dallet包括Dallet那套以法文為基礎的拼法 and the 1959 South Korean school system還有1959年南韓的學校系統 — used the letters "eo"用了「eo」這兩個字母 for the Korean vowel ㅓ來拼韓文的母音ㅓ。Though actually不過其實, English Seoul英文的Seoul is older than比...更早出現 the romanization South Korea uses today南韓現在用的羅馬拼音; the newer system這套新系統 just happens to spell this city the same way只是剛好用同樣的方式拼這個城市名而已。