Problem installing gulp?

Question

gulp.js

Anatolijs-MacBook-Pro:~ anatolijkirsanov$ npm install --global gulp
npm ERR! Darwin 14.5.0
npm ERR! argv "/usr/local/bin/node" "/usr/local/bin/npm" "install" "--global" "gulp"
npm ERR! node v4.2.1
npm ERR! npm v2.14.7
npm ERR! path /usr/local/lib/node_modules/gulp
npm ERR! code EACCES
npm ERR! errno -13
npm ERR! syscall rmdir
npm ERR! Error: EACCES: permission denied, rmdir '/usr/local/lib/node_modules/gulp'
npm ERR! at Error (native)
npm ERR! { [Error: EACCES: permission denied, rmdir '/usr/local/lib/node_modules/gulp']
npm ERR! errno: -13,
npm ERR! code: 'EACCES',
npm ERR! syscall: '
npm ERR! path: '/usr/local/lib/node_modules/gulp' }
npm ERR!
npm ERR! Please try running this command again as root/Administrator.
npm ERR! error rolling back Error: EACCES: permission denied, rmdir '/usr/local/lib/node_modules/gulp'
npm ERR! error rolling back at Error (native)
npm ERR! error rolling back { [Error: EACCES: permission denied, rmdir '/usr/local/lib/node_modules/gulp']
npm ERR! error rolling back errno: -13,
npm ERR! error rolling back code: 'EACCES',
npm ERR! error rolling back syscall: 'rmdir',
npm ERR! error rolling back path: '/usr/local/lib/node_modules/gulp' }
npm ERR! Please include the following file with any support request:
npm ERR! /Users/anatolijkirsanov/npm-debug.log
Anatolijs-MacBook-Pro:~ anatolijkirsanov$

Answer 1

Rule:
everything with --global is installed with sudo npm install ...,
everything without --global is installed with npm install ...,

Answer 2

npm ERR! Error: EACCES: permission denied, rmdir '/usr/local/lib/node_modules/gulp'
npm ERR! Please try running this command again as root/Administrator.

What could it be? Alert the Queen!