This essential cloud-based storage allows us to save files online so we can get to them from any computer. We can share large files with other people, and DropBox integrates with an incredible number of other apps and services so that you don’t need to email stuff to yourself. You start with 2GB of space, but there are a lot of ways to increase it. Many iPad and iPhone apps rely on it to share your data. To install, start with the Mac version to create your account, then install the iOS apps and log in.