In operating systems, upgrades to newer versions are said to be backward compatible if executables and other files from the previous versions will work as usual.
in oPEratinG SYsTems, upgRades to newEr vERSiOns aRe SAid TO Be BAckWarD cOmpatIble IF exeCuTablEs and otHEr fiLes frOm the previOus VeRSioNs wiLl worK as usual.