けど

けど means "but". It sits at the end of the first half of a sentence, straight after です or ます, and the sentence carries on.

けど or でも

でも says the same thing from the other side of a full stop. It starts a new sentence, and けど keeps you inside the one you are in. Joining two polite sentences with でも in the middle is wrong: ×この本は難しいですでも、面白いです.

Leading into a request

けど does not always contrast. It also sets up what comes next: you say who you are or what the matter is, then ask.

Usage notes

These go beyond polite-form けど.

が, the more formal "but"

が goes in the same place and means the same. After です and ます, が is the usual choice in writing and in careful speech, and けど is what you hear in conversation.

After the plain form

Among friends and family the first half is in the plain form. A verb or an い-adjective takes けど directly.

A noun or a な-adjective needs だ in between: ×学生けど. An い-adjective takes no だ: ×忙しいだけど.

Stopping at けど

A sentence can end on けど and leave the rest unsaid. It softens a refusal or a complaint, and the listener fills in the second half.

けれど and けれども

けれど and けれども are the longer forms of the same word. The longer the form, the more formal it sounds.