Hello I am new in backbone. I have following question.
If we just include backbone js and underscore js on html page, still we can use backbone features. Then what is need to install backbone by npm? If it is necessary then please explain.
You don't need to install backbone by npm if you are ok with staying with specific version of backbone and dependencies and updating them manually if you need a version update. Considering backbone is not under active development, this isn't a bad option, especially for small or pet projects. Having a build setup with tools like NPM, Bower etc lets you resolve dependencies and update all libraries easily in case of bigger projects