Open Source Software is software that comes with the source code. Sometimes, only the source code is provided. The benefit to the person receiving the software is that they can make any changes they want at any time. If they find a bug, they can fix it. Also, if the source code is provided, it’s extremely unlikely that there’s any malicious code in the software because it would be blatantly obvious. You can’t really hide malicious code if you provide the source code too. This is only possible if the source code is provided.
There’s a common misconception though about open source software. Not all of it is free. There are many commercial products that charge for their software, but happily give the source code to their paying customers.
Then again, there is totally free open source software too. There seems to be much more of this type of open source software. There are open source software groups and organizations and web sites that do nothing but host or produce free and open source software.
The Linux Operating System is probably the largest example of Open Source software. Linux is a completely free operating system and the source code to it is freely available. Anyone can download and install Linux without having to pay anyone and anyone can get the source code to Linux and make whatever changes their hearts desire.
Here are some good online sources for Open Source software: