Since the hardware is constituted by the circuit, so that all programming languages into binary eventually be used to control opening and closing of the circuit.
The first-generation languages: machine language
This language is a binary language the whole configuration of 0 and 1, are dedicated to the operation of the machine instruction. Different configuration different circuits, the same switching command, so the different machines, the command code is not the same.
The second generation language: assembly language
Because machine language is difficult to read, poor portability, on this basis, it made a slight improvement is the use of certain words on behalf of that particular order, easy to read.
Since you want to use the provisions of the word represent a specific command, which requires a unified standard hardware manufacturers, such as: using the same circuit configuration to control the machine on and off.
This language is still a machine language, portability is still very poor. I guess the reason is that the major manufacturers and there is no uniform standard circuit, this has led to a fragmented, difficult to transplant.
When the machine is unified, it will follow on from that alliance with monopoly.
Assembly language is the most important thing a compiler: the word can be translated into 01 binary machine language by a compiler.
Third-generation languages: high-level language
This language is more and more, such as java, python, c, c ++;
However, the process for the first phase, the second phase is an object-oriented.