Here's a breakdown:
1. "However" within a sentence:
* When "however" introduces a contrasting idea: "I wanted to go to the concert, *however*, the tickets were sold out."
* When "however" is not at the beginning of the sentence: "The weather was terrible; *however*, we still had a good time."
2. "However" at the beginning of a sentence:
* Always use a comma after "however" when it starts a sentence: " *However*, we can always try again tomorrow."
Important note: "However" is an adverb that modifies the entire clause or sentence it's in. When it comes at the beginning of a sentence, it usually creates a pause, which is why the comma is used.
Examples:
* Incorrect: "I love pizza however I don't like anchovies."
* Correct: "I love pizza, however, I don't like anchovies."
* Incorrect: "However we tried to contact them they were unavailable."
* Correct: "However, we tried to contact them, they were unavailable."
Let me know if you'd like more examples or have any other questions!