1. "Too" as an Adverb
* No comma needed: When "too" acts as an adverb modifying a verb, adjective, or another adverb, no comma is required.
* *He walked too fast.*
* *The movie was too long.*
* *She sang too quietly.*
2. "Too" as a Conjunctive Adverb
* Comma needed: When "too" connects two independent clauses, it acts as a conjunctive adverb (like "also," "however," "therefore"), and a comma is necessary before it.
* *The cake was delicious, too.* (This is a shorter way of saying "The cake was delicious, and it was also very good.")
* *I wanted to go to the concert, too, but I was too busy.*
3. "Too" in a Series
* Comma needed: When "too" is part of a series of items, use a comma before it as you would for other items in the series.
* *He likes pizza, tacos, and burgers too.*
Example:
* *I love pizza, too, but I prefer it with extra cheese.* ("Too" connects two clauses, so it needs a comma.)
In summary: If "too" connects two independent clauses, use a comma. Otherwise, no comma is required.