Here's a breakdown:
1. "Also" as an introductory word:
* Yes, use a comma.
* Example: Also, I want to buy some milk.
2. "Also" within a sentence:
* No comma needed if it's part of the main clause:
* Example: I want to buy some bread also.
* Comma needed if it's setting off an additional clause:
* Example: I want to buy some bread, and I also need milk.
3. "Also" after a conjunction:
* No comma needed if "also" is directly after a conjunction like "and" or "but":
* Example: I want to buy some bread, and I also need milk.
In short:
* Use a comma before "also" if it starts a sentence or introduces an additional clause.
* Don't use a comma before "also" if it's part of the main clause or directly follows a conjunction.
If you're unsure, try reading the sentence aloud. If a pause feels natural before "also," then a comma is likely needed.