A cloud storage system is basically an online server with a lot of disk space. When you store files on your computer, you save the files on the hard drive physically installed on your computer. When you store files in the cloud, you upload the files online and save the files on a hard drive connected to an online server.
One of the main benefits of cloud storage is data security. Since your data are stored off-site, they are safe if your computer breaks down or gets stolen. Even in the extreme scenario where your building burns down, your data are safe. In addition, cloud storage allows you to access your computer files anywhere as long as you have a computer or mobile device with an internet connection.