What is Open Source Software?

Open source software, free software or software libre is software that can be used, copied and distributed liberally - modified or unmodified, with or without payment. Free here means freedom of use and this is where its greatest benefits lie. The freedom to modify the source code and hence customise open source software offers:

More control    
Software defects and functions can be tested and repaired when insight into the source code is available. This transparency secures you against hidden features and spying tools, which is especially relevant to security related areas such as firewalls, encryption or VPNs.

More individuality
With the freedom to modify source codes, comes the freedom to customise software. As the basic functions already exist, tailoring the program is much faster and cheaper than writing it from scratch.

More tailored
The usual, proprietary softwares from large companies tie you closely to the manufacturer. As they are the only ones with access to the source code, they are the only ones who can eliminate errors, provide support or improve the software. With open source software, you are dependent on no one and instead have full freedom.

Less Cost
As the software itself usually costs nothing, the only costs involved are for customisation or other additional services and supporting components such as databases, email or web servers.

More support
Large open source projects such as Apache Webserver or Sendmail are used worldwide by hundreds of thousands of users. The product is hence tested, improved and extended upon by this multitude of users and developed in collaboration. In effect you have a much larger and varied support base to draw from.