When you want to run script from other file, or include library, you need to use require or load
Ruby system find library using relative path or absolute path or $LOAD_PATH setting.
If there are no file in these path, LoadErro has happened
Difference between require and load
|Run same file?||Only one time||Run every time to call load|
|File Index||automatically added||not automatically|
I often require in sample source codes
require is similar with import in Objective-C.