"Etc." is used to indicate that only some of the items on a list have been used. Generally, in American English, if "etc." is used in the middle of a sentence, then it is followed by a comma. (Tennis, soccer, baseball, etc., are outdoor games.) However, if this word appears at the end of a sentence, then the period (which is part of "etc.") serves as the final punctuation mark. It should not be followed by a comma. (Being outdoors, we played tennis, soccer, baseball, etc.).