1. As a conjunctive adverb:
* When "however" introduces a contrasting idea, it's usually followed by a comma. This is similar to other conjunctive adverbs like "therefore", "moreover", and "furthermore".
* Example: *The weather was awful. However, we still had a great time.*
* If "however" is placed within a sentence, it's typically enclosed by commas.
* Example: *We had planned to go to the beach, however, the rain forced us to change our plans.*
2. As an adjective:
* When "however" acts as an adjective meaning "in whatever way," it doesn't require a comma.
* Example: *I will handle the situation however I see fit.*
Here are some additional notes:
* The comma after "however" is often optional when the sentence is short and simple.
* The use of a semicolon before "however" is also possible, especially in longer sentences.
To be sure, check the context and see if the comma makes the meaning clearer or more natural.