Software can be thought of as the variable part of a computer and hardware the invariable part. Software is often divided into application software (programs that do work users are directly interested in) and system software (which includes operating systems and any program that supports application software).The term middleware is sometimes used to describe programming that mediates between application and system software or between two different kinds of application software (for example, sending a remote work request from an application in a computer that has one kind of operating system to an application in a computer with a different operating system).For example, without your Internet browser, you could not surf the Internet or read this page and without an operating system, the browser could not run on your computer. The picture to the right shows a Microsoft Excel box, an example of a spreadsheet software program.An additional and difficult-to-classify category of software is the utility, which is a small useful program with limited capability. Some utilities come with operating systems. Like applications, utilities tend to be separately installable and capable of being used independently from the rest of the operating system.Software can be purchased at a retail computer store or online and come in a box containing all the disks (floppy diskette, CD, DVD, or Blu-ray), manuals, warranty, and other documentation.Software can also be downloaded to a computer over the Internet. Once downloaded, setup files are run to start the installation process on your computer.Free softwareThere are also millions of free software programs available that are separated into different categories.
Shareware or trial software is software that gives you a few days to try the software before you have to buy the program. After the trial time expires, you’ll be asked to enter a code or to register the product before you can continue to use it.
Freeware is completely free software that never requires payment, as long as it is not modified.
Open source software is similar to freeware. Not only is the program given away for free, but the source code used to make the program is as well, allowing anyone to modify the program or view how it was created.
Software is often packaged on CD-ROM and diskettes. Today, much purchased software, shareware, and freeware is downloaded over the Internet. A new trend is software that is made available for use at another site known as an application service provider.Some general kinds of application software include:
Productivity software, which includes word processors, spreadsheets, and tools for use by most computer users
Graphics software for graphic designers
Specialized scientific applications
Vertical market or industry-specific software (for example, for banking, insurance, retail, and manufacturing environments)
Firmware or microcode is programming that is loaded into a special area on a microprocessor or read-only memory on a one-time or infrequent basis so that thereafter it seems to be part of the hardware.