Most Common Unix Applications Are Open-Source

Since most of the common or important Unix applications or utilites are also open-source, this means that Linux automatically has thousands of applications to choose from. These include everything from common utilities to large-scale applications like Apache, the most popular webserver on the planet.

Almost all new development explicitly includes a Linux port, so more are available all the time. In fact, most new Unix programs are developed on Linux first, or at least in parallel. Even commercial developers tend to run Linux on their PC's at home, so they can use the same tools, compilers, and environment they have with their commercial Unix workstations at work.