"But" is used like "and" to join sentences, but it implies that there is a contrast between the two clauses. It suggests that there is something surprising in the second clause relative to the first. "And' is neutral -- merely supplies a link.
Example: Ed is the center on the football team and he is from New York.
Sam is the center on the football team but he only weighs 150 pounds.
This is a sentence using the word monomer. :P
Explain briefly why do you want to join Ecolog*
We had to join an alliance to defeat the other basketball team.
They had a long journey ahead of them. Will you join us on the journey to Spain?
This is known as a join operator
JOIN operator
Gentleman on his early career move to join the Liberal Democrats rather than the Labor party.
Yes, a semicolon could indeed join an incomplete sentence and a complete sentence.
I wanna join in the party?
although he was not old enough to join the club the members viewed him as an honorary member
She happily skipped off to join her friends. The story ended happily for the trio.
We met somebody who told us that he had been to the moon.