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Software Lexicon: Software Lexicon

How do you know whether the software you're downloading is truly free? And what does "free" mean exactly, anyway? Here's a quick guide to the terminology of free and almost-free software.

adware Advertising-supported software or Web services. Often (but not always), a paid alternative lets you remove the ads.

freeware Programs that you can download, install, and run without charge or limitation of any kind. Freeware may be from a company or an individual, who may or may not provide support.

malware or badware Malicious software--often installed surreptitiously alongside seemingly legitimate free programs--that can slow down your computer, insert extra ads into Web pages, and spy on your online activities.

open source Software that is free to run--and for which the source code is available, so you can modify the software (if you're a programmer). Most open-source software is supported by volunteers, if at all.

shareware Software that is free to run for a limited time, after which you're asked to pay a fee. Shareware may "nag" you to register (and pay) after the trial period is done, but should remain fully functional.

trialware or demoware Software that you can run for a limited time, after which it stops working unless you purchase the full version. In some cases the demo may continue to function but loses certain features after the demo period. We've included a few demos in this roundup, but only if they remain substantially useful without purchase.