Why and How To: Grunt and Gulp
The following articles will give you a very good overview on Grunt and Gulp.
Grunt and Gulp are package managers for front end development.
npm (node package managers is another alternative, some prefer to stick to npm than using grunt and gulp). Grunt and gulp also needs npm.
Composer is PHP package manager
Nuget is the package manager for .Net platform (C#, VB.net)
Maven is the package manager for Java. A project and it's dependencies are described in an pom.xml file. However, maven is way more than a package manager.
Grunt, Gulp, and NPM