what is node modules how to install this

angular-quickstart

app

app.component.ts

app.module.ts

main.ts

node_modules ...

typings ...

index.html

package.json

styles.css

systemjs.config.js

tsconfig.json

typings.json

hi guys am a beginner in angular2 ,i dont know how to install the node module inside my project .you guys can see that project structure .i have the doubt over there i completed everything except this Node module .actually what is node modules why its come to angular js can you please any give the solution for this

is there any nuget package available for this (node module)