Illustration of cloud computing

One of my students asked me last night for a definition of data being “in the cloud”, and I realized I had not written an article on the topic, so here goes.

“In the cloud” simply refers to applications and/or data being stored on the Internet, rather than on a specific device. This means that your data can be retrieved, shared and modified from any device with an Internet connection.

Cloud computing is nothing new: it is a derivation of a practice common since the 60’s. Modern browsers, databases, and technology such as AJAX have meant the idea of storage of individual data on a central server can be transferred to the web.

Some advantages and examples of cloud-based services include:

iTunesElimination of redundancy
Rather than having to keep copies of music on different devices, requiring you to re-sync them when new purchases are added, Apple’s latest version of iTunes stores your purchased music on a server, which every Internet-enabled device can draw from wherever you happen to be.
Mitigation of loss
DropboxOnline backup and file storage services, such as Dropbox , iCloud and Carbonite back up your important data in the cloud, allowing you to recover it even if your devices are destroyed.
Synchronization of data across multiple devices
Enabling “Google Sync” on the Chrome browser or mobile device (and similar services for others, such as Xmarks or iCloud) means that other copies of your browser (like the one on your office machine or mobile device) share browsing history, bookmarks, extensions, gMail data, and login information.
Constant availability
Google DocsStoring your presentation on a cloud-based service such as Google Docs avoids the often-experienced scenario of “Oh, no! I left the presentation on my laptop at home!” So long as your location has an internet connection and you have a device with a browser, you can retrieve it.
Easy sharing
Traditionally, having multiple people work on the same document and trying to integrate their edits and suggestions into a single work has been a nightmare scenario. Microsoft’s latest version of Office, as well as CloudConnect, Google Docs and other services, allows nominated users to contribute changes to a single, shared document that is updated in real time for everyone to see.

Cloud computing is not perfect, and does have a few requirements:

Server uptime
If the servers that hold your information go down for any reason, you lose access to your data. Most cloud-based services offer some form of local storage option to mitigate this, allowing you to backup your data from the cloud onto your own device.
High-speed connection
Especially for online backups or large documents, having a reliable broadband internet connection is a must, as you will be downloading and uploading data to and from the service on a regular basis.
Keeping personal data perpetually on a central server creates a rich target for black-hat hackers, with potentially a single point of failure, as Sony PS3 users have recently discovered. Any personal information saved on a cloud-based service should be encrypted, and accessed via a secure connection.

Cloud-based services are useful - I employ all of the services I have discussed here, with the exception of online backups. (With 16 terabytes of data at home, no Internet-based backup service is going to make economic or practical sense for me, at least at this time.)  Increasing penetration of broadband and mobile devices is also likely to make cloud services are inevitable; I encourage you to check them out, and provide your own recommendations in the comments.