Marc Saltzman

USA TODAY

Smartphone owners carry important files on them – documents, irreplaceable photos and videos, for example. What are you doing to back-up your device in case it’s lost, stolen or damaged?

There are a few solutions, such as syncing the phone with a computer via USB, or inserting a microSD card (for Android) or Lightning flash drives (for iOS), but one of the cheapest and easiest ways to safeguard your smartphone is by taking advantage of free cloud services.

Question is, which one should you go with?

Before we get into the differences between five of the more popular cloud services, a word on what we’re talking about here.

What's the big deal about cloud?

Instead of – or in addition to – storing your files locally on your device, a cloud service lets you store and access your files in a password-protected online locker, of sorts.

Offsite protection: Cloud services can protect your data from local threats, such as theft or damage. Snap a photo on your iPhone or Galaxy and you can have a copy immediately uploaded to a cloud drive for safe keeping.

Anywhere access: With cloud services, you can access all your backed-up stuff – such as documents or media — from virtually any Internet-connected computer, tablet or smartphone in the world. Yes, you need to be online, but it doesn’t matter from where.

File transfer: Cloud services can also reduce congestion in someone’s inbox. Rather than trying to email several large photos or videos to a colleague or family member, you can simply store them in the cloud and send a link to download.

Real-time collaboration: Students or colleagues can often collaborate on a cloud-stored document in real-time, even though they’re in different physical locations. This could be a more efficient process than sending revisions back and forth to one other. There’s also software-as-a-service (“SaaS”) that only runs in the cloud, but we’re not talking about that here.

They’re free, secure: While you might only get a few gigabytes to get going, cloud services won’t cost you anything to store your files. You will need a password to access your files, and most cloud services also offer two-step authentication, which also requires a one-time code sent to your device, which you must type in, to prove it’s really you.

Related: Running out of iPhone storage space? These trips can help

A look at the big players

You’ve got some choice when it comes to cloud services for your smartphone (and tablet, laptop, and desktop). Many of them have similar features, but here’s a snapshot and a few of the more popular picks (note: Box now focuses more on the business space than consumers, and so we’re not including them in this round-up).

Dropbox

The granddaddy of cloud services, Dropbox supports multiple operating systems, and its clean and simple interface means its perhaps the easiest to use out of all the cloud providers, but it only offers 2 gigabytes (GB) of free storage – much less than other cloud providers. That said, your storage can be significantly increased by referring friends, linking to social media, and through other opt-in ways.

Upload files from your phone, tablet or computer; send large files to someone (even if they don’t have a Dropbox account); and you can edit Microsoft Office files like Word or Excel from your mobile device. If you like, you can have all captured photos and videos automatically upload to Dropbox. Dropbox Plus costs $9.99 a month for 1 terabyte (TB).

Google Drive

Especially for Android users as it’s already integrated into the operating system, Google Drive offers up to 15GB of free storage, which is ample for most casual users, plus it works seamlessly with Gmail, allowing you to save attachments to Google Drive (or sending an email right from Google Drive).

You can now upload high-definition photos from your mobile phone with Google Drive’s companion app, Google Photos.

Similar to other services, once your files or folders are uploaded to your drive you can easily invite others to view or edit (or leave comments). Along with fast search, you can enable offline viewing of specific files, scan paper documents, and more.

Unlike Dropbox and OneDrive, you cannot earn additional storage. More storage will cost you $1.99/month for 100GB, $9.99/month for 1TB, or $99.99/month for 10TB.

iCloud

Ideal mostly for iPhone and Mac users, iCloud is already integrated into the iOS operating system.

But since you only get 5GB of free storage, expect to get a message about running out of space pretty quickly – especially if you’ve enabled photo and video backup. iCloud is also seamlessly woven into Mac’s Finder app, along with saving your work to the cloud via iWork, and there’s support for Windows users, too (one-time download is required). Or log in at iCloud.com.

Along with documents and media, iCloud also lets you sync contacts, calendars, email and bookmarks between iOS devices, Macs and PCs. Now, anyone can freely use Pages (word processor), Numbers (spreadsheets) and Keynote (presentation maker) inside of iCloud, as well.

You cannot earn additional storage like you can with Dropbox and OneDrive, but costs are more reasonable for additional iCloud storage: $0.99 cents for 50GB/month, $2.99 for 200GB, $9.99 for 1TB, and $19.99 for 2TB.

Microsoft OneDrive

Just as Google Drive is integrated with Android, and iCloud built into iOS, Microsoft’s OneDrive is already part of Windows 10. In fact, when you set up a computer for the first time, you’ll be prompted to create a OneDrive folder in Windows Explorer (or add it later on). There’s a Mac version, too. But if you’re an avid Windows user, OneDrive is for you.

With the OneDrive app for phones and tablets, you’ll get the same 5GB of storage for free (or 50GB for $1.99/month), or better yet, with an annual Office 365 Personal subscription ($69/year), which includes Word, Excel, PowerPoint, Outlook, and so on), you’ll get 1TB of OneDrive storage. Office 365 Home ($99/year) provides 5TB of storage for the family (up to 1TB/user).

Features include the option to automatically upload captured photos and videos; receive notifications when a shared document is edited, easily find photos on your OneDrive (thanks to automatic tagging), and even annotate and sign PDF files stored online.

Amazon Cloud Drive

Whether you use the app for mobile devices or computers, Amazon Drive gives you access to your photos, videos, music and documents (which you can edit, too). It really shines in the photo department as Amazon Prime members ($99/year) get unlimited backup. Otherwise, it’s a reasonable $11.99/year for unlimited photo storage (and 5GB for everything else), or $59.99/year for unlimited everything -- which is the best overall deal between all cloud providers at only $5/month.

Like the other services, you can play music and videos in your drive without having to download them. Search and share your files with others, by sending a link to the file(s) you give permission to access, and you can rename and move files and folders, too.

USA TODAY readers, which cloud provider do you use, and why? Feel free to share in the Comments section. Follow Marc on Twitter: @marc_saltzman. E-mail him at askmarcsaltzman@gmail.com.