You may be used to accessing your Dropbox files from any device connected the internet, but what you might not realize is that Dropbox syncs those files to your computer's hard drive.
That can take up a lot of space.
But soon Dropbox will release a new service called Dropbox Infinite, which gives you access to all your files without taking up any space on your computer. The files will still show up in the Dropbox folder on your Mac or Windows PC, but won't download until you attempt to open them.
Of course, the caveat here is that you won't be able to access your files if you're not connected to the internet. However, Dropbox will let you download the files you use the most for offline use.
Dropbox Infinite will only be available for business users at first, but it seems like the next step will be to bring it to individual accounts too.
Here's a video from Dropbox explaining how Dropbox Infinite works: