Open-source software should not be confused with freeware, or software that is available to install free of charge. While most open-source software is free, there are many other criteria – namely that the source code must be available to the general public via an open-source license, and that anyone is allowed to modify it. Any modifications made must also be distributed under the same terms as the original software. Proponents of the open-source movement believe this collaborative development methodology results in quicker improvements and software that can be easily adapted to users’ needs. Financial savings are another main benefit of open-source software. Because numerous programmers are able to identify and fix problems, advocates believe open-source software is more reliable than proprietary software. The majority of commercial software protects its source code to prevent competitors from developing a competing product. By only making a compiled, ready-to-run version available, software manufacturers retain full control over their product, which they argue ensures higher levels of quality and security. End-users must purchase a license fee, and typically benefit from a warranty and technical support. Although open-source software does not charge license fees to fund its development, it does not follow that it cannot be commercially viable. Developers charge for installation, training and technical support. Alternatively, licenses for add-ons and additional software may be sold.