Dropbox - Secure backup, sync and sharing made easy.

Dropbox is the easiest way to store, sync, and, share files online. There's no complicated interface to learn. Dropbox works seamlessly with your operating system and automatically makes sure your files are up-to-date. Available for Windows, Mac, and Linux.

disclosure: I will get bonus space if you join via the link below. still it is a great service even without the bonus.

https://www.getdropbox.com/referrals/NTI3NTkzOTM5