ITunes:

This software is a multimedia player, a software application for managing mobile and media libraries developed by Apple to play, download and organize audio and digital files on OS X and Microsoft computers. Windows is also on the iTunes Store on the iPod, iPhone, and iPad.
Through the iTunes Store, users can purchase and download music, video music, television shows, audiobooks, videos, ringtones, podcasts and software.

ICloud:

It stores your music, photos, videos, software, documents (Documents in the Cloud), calendars, and more wirelessly and automatically between your devices. Entering this software gives you 5GB of free volume, which is the perfect size for storing your photos, emails, documents, files and more.

ITunes and iCloud connection:

For example, with your iCloud music purchased on iTunes, it will appear on all your devices. You can also download your latest purchase from iTunes whenever and wherever you want. Download your favorite music and finally with iCloud automatically on You'll have all your devices