# 2021q1 Homework1 (culture)
contributed by < `ilkclord`>

## Free Software

Free software can be used by everyone , and can modify the sourcecode .To prevent the company use the source code of software to make their product . The concept 'Copyleft' were invented .It is the rule you have to obey when you use the software , and it will be passed to the next owner . So if a 'Copyleft' say that everyone can used this software , the next owner needs to make it public when published.

## Open Source

Open source has few more rules to follow.
* conserve the authors right

To prevent author from being forced to published the source code , Open source gives the athor the right to cancel publishing
* stay neutral

To let the code be " clean " ,Open source won't have bias via everything.

## Earn

People master in computer science can earn their profit by mantaining their Open source code , or coding a sepecific project for company .

## Unix
Unix system is a very eraly OS that has strong function . The system creates the file systems , and has a new concept of programming .They break programs into small process , which is very functional.Users can use those tools to complete their task , also they can take tools to form a new program . It is just like library in nowadays !
## GNU

GNU systems were invented because the programmer thinks the OS(operating system) shouldn't be for sell .They want to create a world that everyone can use a computer .So they start developing GNU system .The GNU system is base on Unix system , becase of concern to the Intellectual property rights , they have to rewrite each process in Unix system.

## Linux

While the kernal of GNU systems is gonna to be completed , they discovered a kernel called Linux hacked by Linus ,a man from Finland .The kernal is much more stronger then the kernal they wrote , so it is plugged in to the system .GNU/Linux system is born !

reference : https://mropengate.blogspot.com/2016/02/revolution-osthe-code.html