‘and’ and ‘but’
“and” and “but” join clauses into a sentence.
Do not start a new sentence with “and” or ‘but”.
Do not put a comma or a full stop before ‘and’, ‘but’ or ‘or’.
Do not put a comma after a conjunction introducing a clause, e.g. He told me that he was too tired to watch the movie.
Traditionally, ‘however’ was regarded as a conjunctive adverb or a discourse marker, not a conjunction. In other words, ‘however’ marks a relationship between sentences or ideas and does not join clauses into a sentence, i.e. it is not a conjunction.
However, the Macquarie Dictionary notes that there is a modern trend to use it as a conjunction and gives the example: I thought he was coming, however he failed to arrive.