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C# is the latest progression in a never ending quest to make it as easy and efficient as possible for humans to program computers. Whilst it would be easy to simply describe C# as just another object oriented programming language developed by Mcirosfot and ratified by ECMA and ISO, the fact is that C# is actually an integral part of an entire development and execution infrastructure. There primary object of this chapter of [[C Sharp Essentials|C# Essentials]] is to provide an overview of both the C# language and the infrastructure on which it relies. By the end of this chapter it also is intended that the reader will have a clear understanding of what acronyms such as CLI, CLR, VES, JIT and .NET mean.

The problem with programming is that computers think exclusively in numbers (the numbers 0 and 1 to be precise) known as ''machine code'' while humans communicate using words. In the very early days programmers actually entered machine code directly into computers to program them. This, as you can imagine, was a laborious and error prone process. The next evolution was to associate brief human readable commands with the corresponding machine code. For example, a programmer could enter the command ''MOV'' to transfer a value from one microprocessor register to another. These commands would then be translated into machine code by a piece of software called an ''assembler'', thereby giving this command syntax the name ''Assembly Lanaguage''. Next came a series of ''high level'' languages designed to make it easier for humans to write programs. These programs are written using a human readable syntax and then either compiled to machine code by a ''compiler'' or interpreted on behalf of the processor by an ''interpreter''. Such languages include BASIC, COBOL, Pascal and Fortran. One other such language is called ''C'' which was created at AT&T Bell Labs in the late 1960's and early 1970's. In the late 1970's and early 1980's work started on an object oriented approach to C programming culminating in a new, object oriented variant of C known as ''C++''. The story, however, does not end there. The problem with C++ was that it was an incredibly easy language in which to make programming mistakes. C++ would quite happily allow a programmer to make coding mistakes that would cause buffers to overflow, memory location to be arbitrarily overwritten and introduce memory leaks that would cause applications to bloat to the point of using up the entire physical memory and swap space on a system. Another problem encountered with C, C++ and all other compiled languages is the fact that the source code has to re-compiled for each different processor type making it difficult to port an application from one hardware platform to another.