A software application is said to be compatible when It can. run efficiently on all the versions and various variations of a computer system or model. Compatibility can either be in terms of the system hardware or the type and versIOns operating systems. It can also refer to forward orbackward compatibility.
When an application can work well with older versions of an operating system is called as backward compatible Whereas if an application requires any type of a system upgrade either with respect to hardware or the operating system, it is said to be forward compatible. Forward compatibility is usually for newer versions of an application which will not affect any files created using the prior versions of the same software.