Dropbox is a file hosting service operated by Dropbox, Inc., that offers cloud storage, file synchronization, and client software. Dropbox allows users to create a special folder on each of their computers, which Dropbox then synchronizes so that it appears to be the same folder (with the same contents) regardless of which computer is used to view it. Files placed in this folder also are accessible through a website and mobile phone applications.

Dropbox, Inc., was founded in 2007 by Drew Houston and Arash Ferdowsi, as a Y Combinator startup company.

Dropbox provides client software for Microsoft Windows, Mac OS X, Linux, Android, iOS, BlackBerry OS and web browsers, as well as unofficial ports to Symbian, Windows Phone and MeeGo.

According to Dropbox, founder Drew Houston conceived the idea after repeatedly forgetting his USB flash drive while he was a student at MIT. He says that existing services at the time "suffered problems with Internet latency, large files, bugs, or just made me think too much." He began making something for his personal use, but then realized that it could benefit others with the same problems. Houston founded Dropbox, Inc. in June 2007, and shortly thereafter secured seed funding from Y Combinator. Dropbox officially launched at 2008's TechCrunch50, an annual technology conference.