File suddenly much smaller, what happened?

[chablups]

I just started using Access about a week ago. My file that had been 57MB, has now become my backup file, and another file was created with the same name as my original file but it is only about 7MB. I didn't do this, the program did it all by itself. I copy to a zip to keep another computer at home updated and everything seems to work fine with the smaller file. In fact it's great because it copies so much faster, but what happened to the other 50 million bytes?

 

[chablups]

Thanks Pat. So am I safe using the compacted copy to my zip disc in case my computer were to crash? It seems to work just fine when I copy it from my office computer to my home computer, and it copies so much faster that the backup copy which as I said is 57MB compared to the compacted copy which is only 7MB. Also, is there some reason one would not want to compact on close? (I apparently activated it by accident.) It sure saves a lot of time copying the file.