Why NPM:
When the number of package introduces a lot of time management has become a problem, this is a convenient place npm line for developers, npm has already done the dependency and version control for you, that allows you to use npm from the complex dependencies installation and version conflicts freed, and then focus on managing your business, not the library
Webpack
webpack is a tool, which can help you handle dependencies between various packages / modules (modules with dependencies), static files and package these complex dependencies into one or a few static files to the browser access use; in addition, webpack because they can increase compatibility, but also may be some browsers do not yet support the new features supported formats can be converted , thereby reducing the new features brought by the browser compatibility issues
webpack your installed from npm packaged into smaller packages in browser readable static resources, to note here is that, webpack just a front-end packaging tools, packaging is a static resource, and the background does not matter, though webpack dependence to node environment
And Node Relationship: Based node created to support all Node API and syntax