One of the biggest terms in computing nowadays is “cloud computing.”

While the definition is still evolving, companies such as Amazon, Microsoft and Google are reporting huge gains in their cloud computing businesses.

According to the most recent financial reporting and industry analysts, cloud computing for each company is well into the billions of dollars per year, if not per quarter.

So what is all of this cloud stuff and why should you care?

It’s really pretty simple. Despite all of the massive computational horsepower you have on your computer at home or your smartphone, that’s nothing compared to the power that resides in large data centers.

These data centers are huge, sometimes measured in football fields. They have processors and storage (typically disk) that goes on seemingly forever.

These data centers offer things that are typically very difficult for individuals or companies to address, such as very high up-time, backups, duplicating data in different data centers, security, ability to add more computing power on demand for short or long periods of time … all very cost effectively.

Some of the things that people use frequently that can be considered cloud computing include Google’s Gmail email service, voice recognition on your smartphone and navigation systems on smartphones, but the list is huge.

With each of these services, your computer is frequently primarily a display device (we used to call these “terminals”) and the bulk of the computing is done somewhere else.

For example, when you speak to your phone asking: “What is the weather on Halloween?” the audio of what you asked is sent to a data center where it is converted to something else, typically text, then analyzed to figure out what you’re asking, when Halloween is, where you are, etc.

Once the computers in the data center have figured out what you’re asking and have looked up the answer, they present it to you on your screen and possibly by voice.

No individual computer has the speed or connections to do all of this work on the computer or smartphone itself.

There are two main challenges that people have with cloud computing.

If you’re a business, the challenge is the privacy and sanctity of data you own that’s under someone else’s control in their data center. For banks, hospitals and other organizations that regularly handle sensitive information, letting someone else hold your information is a huge risk.

For normal consumers, cloud computing is most frequently valuable when mobile, typically through your smartphone.

So, if you’re in an area where you do not have access to the Internet, your ability to use your cloud services can be hampered. If you’re in your car, on an airplane, in a rural area or anywhere that you don’t have access to the Internet, services you may come to expect as being always available, may not be so.

Cloud computing services will continue to grow in popularity for the foreseeable future. Mobile connectivity will also continue to cover more geography. The services that we come to expect — and even rely upon — will continue to grow.

This is one of the times when cloudiness is a really good thing.

Mark Mathias, a 35-year information technology executive, is a resident of Westport. His columns can be read at http://blog.mathias.org online. He can be contacted at livingwithtechnology@mathias.org.