"Is there a difference between 추워요 & 춥습니다?" They mean the same thing, but are different in speech style and politeness. In Korean every verb and adjective can be said in different styles, as follows: * Speech style (formal vs informal) - informal: smooth style - for friends, family, and anyone familiar - formal: stiff style - addressing a multitude or strangers, or writing impersonally * Politeness level(casual vs polite) - plain: casual - for familiar people roughly your age or younger - polite: respectful - for those who are senior to you in age/position ( "plain" level is often called "casual" too ) There are other endings, but the above four are good basis for new learners. In daily life, informal-plain is the most commonly used style, followed by informal-polite. The formal styles are mostly used in public addresses (e.g, radio and TV broadcast), formal meetings and lectures, and talking to strangers. The usage pattern is not rigidly fixed, however, and people may mix two or more styles in the same conversation. Examples (using present tense). 춥다 (to be cold) - "춥다" is the root form, or the "dictionary form" 1) 추워: informal, plain 날씨가 추워. 2) 추워요: informal, polite 날씨가 추워요. 3) 춥다: formal, plain 날씨가 춥다. 4) 춥습니다: formal, polite 날씨가 춥습니다. * for adjectives, "formal-plain" style and root form have the same ending. 이다 (is/am/are): 1) 이야/야: informal, plain. 나는 학생이야. 2) 이에요/예요: informal, polite. 나는 학생이에요. 3) 이다: formal, plain. 나는 학생이다. 4) 입니다: formal, polite. 나는 학생입니다. 하다 (to do, perform): 1) 해: informal, plain. 그는 일을 해. 2) 해요: informal, polite. 그는 일을 해요. 3) 한다: formal, plain. 그는 일을 한다. 4) 합니다: formal, polite. 그는 일을 합니다.