What is the "source"?

Hi Guys! I'm new to this forum, and indeed in terms of flyff developments. Not so long ago I was interested in development of servers (about a month ago), I saw a video on YouTube and I was curious. I downloaded a lot of servers and releases, but they were without sources. Only recently I read on the forums what any update can not be established without source (weapons, armor, CS and is). I've been looking for any information about the source, but nothing valuable and useful and did not find. So help me out guys, I have a couple of questions on the topic of source :3

1) What is the source and what is it for?

2) How can I find the source for my server and how it can be installed?

3) How to use the source?

P.s. Very sorry for my bad english =((
Thanks in advance for your answer and help!! <3

First of all, the "Source" is the base Code of all 7 Servers(Like Loginserver,Worldserver and so on) plus the Gameclient. So if you want to change some "bigger" things, you will need the whole Source to compile your new Servers/Client(Neuz.exe).

Also you should download some Files where the Source is already included, so basically you only need to change some paths and small things to make it work.

The following Threads may help you alot(for further Questions too):
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