Under which licence is the Linux kernel released?

The correct answer is C, system software. System software manages the machine itself and gives other programs a place to work: it includes the operating system, device drivers, the language translators and the utility programs. Option A is wrong because utility software is only one part of system software, the housekeeping part such as antivirus and disk defragmenter, and it does not by itself provide a platform. Option B is wrong because firmware is the software written permanently into a chip, such as the BIOS on a motherboard, so it is tied to one piece of hardware rather than being the general platform. Option D is wrong because application software is what the user opens to do work, such as a word processor or a browser, and it runs on top of system software rather than providing the platform.

The correct answer is B, disk defragmenter. A defragmenter is a classic utility: it rearranges the scattered pieces of files on a disk so that the drive can read them in fewer movements, which is housekeeping work rather than work the user set out to do. Option A is wrong because MS PowerPoint is general purpose application software, a presentation package. Option C is wrong because Oracle is a database management system, again application software, even though it is used by programmers rather than ordinary users. Option D is wrong because Linux is an operating system, which is system software but not a utility; the operating system is the platform, while utilities are the small service programs that maintain it. Antivirus, disk cleanup, backup tools and file compression tools are the other standard utilities to remember.

The correct answer is D, freeware. Freeware costs the user nothing, but the licence allows only use: the source code stays with the owner, so the program cannot be studied, modified or redistributed in a changed form. Adobe Acrobat Reader, Skype and Google Chrome are the examples usually named. Option A is wrong because open source software is defined by exactly the opposite feature, a published source code that may be read, changed and passed on. Option B is wrong because shareware is free only for a trial period or in a cut-down version, after which payment is due. Option C is wrong because public domain software carries no copyright at all, so it may be used and altered without any licence. The trap in this question is to read free of cost as open source; the test is the source code.

The correct answer is C, shareware. Shareware follows the try before you buy model: the publisher lets anyone download and use the program for a trial period, or in a version with some features locked, and asks for payment or registration if the user wants to go on. WinZip and WinRAR are the examples most often quoted. Option A is wrong because freeware never asks for payment at all, however long it is used. Option B is wrong because public domain software has no copyright holder to charge a fee. Option D is wrong because open source software is identified by an open source code rather than by a payment model; most open source programs are free, and none of them locks features behind a trial clock in the way shareware does. Remember shareware by the word trial.

The correct answer is C, Linus Torvalds. Linus Torvalds, then a student in Finland, wrote the Linux kernel in 1991 and released it under the GNU General Public License, which is why Linux is the standard example of open source software in question papers. Option A is wrong but is the closest trap: Richard Stallman began the GNU Project in 1983 and founded the Free Software Foundation in 1985, and the GNU tools are combined with the kernel in a full system, yet he did not write the kernel. Option B is wrong because Dennis Ritchie created the C language and, with Ken Thompson, the Unix operating system, which Linux resembles but does not descend from. Option D is wrong because Bill Gates co-founded Microsoft, whose Windows is proprietary software, the opposite of the open source model.