What's 'OPEN SOURCE' ?

[shivamsharma]

Everyone is talkin bot open source but i'm unable 2 get wat xcatly it means .
i've heard bot smthng caled UBUNTU dats sum os , nd a os 4 mobiles ANDROID , but wats new in dem why : ol are goin 4 it.
And last year i heard abot sumthng called Open Source for Computer Aided Drug Discovery Do anybody hv any idea abot dis thing, i searched it but didn't got it.
Anyone havin any idea plz post..

[prkhr4u]

open source is a philosophy,which entitles us many things

for the time let's that the source code is open unlike windows.we can see the full code of software

ubuntu and android are open source operating systems
ubuntu is developed by canonical,while android by google