Flair Minds

Well, to understand this you have to go a little back in history and also think from Machine's perspective as we are talking about machine independence here. So, if you think from machine or processor's perspective, Intel's processor has a different instruction set than that of AMD or any other manufacturer hence it needs different binary code to be able to run or execute a program. Essentially, any compiler needs to generate binary code that is compatible or understandable by the underlying hardware. When C was born (1970s), many other programming languages then used to have only machine specific compilers which could only run on specific processors in turn machines. C became popular so quickly that every hardware vendor has got a compiler written for it and thus, programs written in C could be compiled and run or executed on any hardware vendors (Intel, AMD, etc) machines. Thus, it became a machine independent language compared to other historical programming languages available then. hence, it's called machine independent or portable. That said, the later generation languages such as, Java/C# are machine independent too. In case of C it was an important distinction from other programming languages available at that time and hence it's mentioned explicitly.