meanning of quarantine

Dear All
NOD32 have a modual named quarantine ,and we can add a file to this quarantine . I have tested ,after I have add a .exe file to this quarantine ,the .exe file still remain in the original location (seems NOD32 have Copy not move this file to quarantine ),Here is my question ,what's this quarantine function for ?Since the orginal file is still there ...(Kaspersky will move file to quarantine ,not copy ).
anybody can explain this ?

 

In an alert window you have an option to delete an infected file as well as a check-box which, when ticked, will ensure that the original file will be copied to quarantine before you choose to delete it.