Cross-platform Software
In order for software to be considered cross-platform, it must be able to function on more than one computer architecture or operating system. This can be a time-consuming task given that different operating systems have different application programming interfaces or APIs (for example, Linux uses a different API for application software than Windows does).
Just because a particular operating system may run on different computer architectures, that does not mean that the software written for that operating system will automatically work on all architectures that the operating system supports. One example as of August, 2006 was OpenOffice.org, which did not natively run on the AMD64 or Intel 64 lines of processors implementing the x86-64 64-bit standards for computers; this has since been changed, and the OpenOffice.org suite of software is “mostly” ported to these 64-bit systems . This also means that just because a program is written in a popular programming language such as C or C++, it does not mean it will run on all operating systems that support that programming language—or even on the same operating system on a different architecture.
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