laptop storage suddenly full

I'm working with a 2015 MacBook growth 1TB of storage and runningBig Sur (11.7.7). I fired up the laptop several days ago to a message that my storage was almost full. This surprised asI have not added anything new. All I can determine is there is a group of "other" that occupies most of my storage. I would like to know how this happens and what I can do to clean out the "other" and get my machine back. Thank you.