Dropbox is a cloud storage and sync service that, on the Mac, can make sure anything in its special folder is kept safe online and mirrored on any other Mac you install it on. On iOS, the Dropbox app gives you near-line access to all the same files. What's more, Dropbox provides a powerful API for developers that allow many other apps to tie into their service and use them for cloud storage and sync as well.
Once you've installed Dropbox on your iPhone, iPad, or Mac, you can instantly start saving and syncing files. One staple feature of Dropbox that makes it a convenient file storage solution is the ability to share links to files with others. Many of us have come across a time where we needed to send a file to someone only to find it rejected by an email server due to file size. This is where Dropbox comes in handy. Just create a share link and email the link instead. The person on the receiving side doesn't even need a Dropbox account in order to download it.
On top of easy file sharing and storage, many others app use Dropbox to store files and settings. For example, several mail apps for both Mac and iOS use Dropbox to safely store attachments or user preferences. Some examples of this are the Mailbox, which is now owned by Dropbox, and apps like 1Password which can sync your keychain to all devices via Dropbox.
Dropbox is one of the most widely accepted cloud storage services on the planet not only by its users, but by the developers that choose to support it in their apps. You can download Dropbox on the iPhone, iPad, and Mac at no cost. You also get a few gigabytes of storage space for free. If you need more space, you can subscribe to a monthly Dropbox plan. For businesses that need large amounts of space, Dropbox has special team pricing as well.