Adware is free software that is supported by advertisements. Common adware programs are toolbars that sit on your desktop or work in conjunction with your Web browser. Adware – that collects data with your consent – should not be confused with Trojan spyware programs that collect information, without your permission. If Adware does not notify you that it is gathering information, it is regarded as malicious – for example, malware that uses Trojan-Spy behaviour. The justification for adware is that it helps recover programming development costs for the software developer, and reduces or eliminates the cost for the user. Most adware is safe to use, but some can serve as spyware, gathering information about you from your hard drive, the Web sites you visit, or your keystrokes. Spyware programs can then send the information over the Internet to another computer. So be careful what adware you install on your computer. Make sure it is from a reputable company and read the privacy agreement that comes with it.