What is a USCIS online account and do I need one?

A myUSCIS online account is a personal account at my.uscis.gov that lets you interact with USCIS electronically for certain case types — checking status, receiving electronic notifications instead of only paper mail, updating your address, and in some cases responding to Requests for Evidence online rather than by mail.

You don't strictly need one to check your case status — the receipt number from your paper notice works fine for that, whether through USCIS's own tool or through a tracker like this one. But if USCIS has linked your case to an online account, some communications may only appear there rather than by mail, so it's worth creating one and checking it periodically once you've filed.