What is SaaS? A plain-English guide with examples

Someone in a meeting said “the new tool is SaaS” and you nodded. Now you have to explain to your team why you are paying every month for software you do not own. Here is the short answer: SaaS is software that lives on the vendor’s servers, that you use through a browser or an app, and that you pay for as a subscription instead of buying once.

That one change, from owning a copy to renting access, explains most of what is different about SaaS: the price, who fixes problems, where your data sits and why the bill never stops. This guide covers each of those, with real products and real numbers, so you can explain it to someone else tomorrow.

SaaS in plain terms

Think of the difference between building a house and renting a furnished apartment. When you build, you buy the land, pay for the construction, and every repair afterward is yours. When you rent furnished, you move in today, the landlord fixes the boiler, and you pay rent for as long as you stay. You get less control over the walls, and you never stop paying.

Traditional software was the house. You bought a license, installed the program on your own computers or servers, and your IT team handled updates, backups and security. SaaS is the furnished apartment. The vendor installs and runs the software once, on its own infrastructure, for thousands of customers at the same time. You sign in, you use it, you pay monthly or yearly.

The US National Institute of Standards and Technology (NIST) wrote the definition most of the industry uses, in Special Publication 800-145 (September 2011). It describes SaaS as the capability “to use the provider’s applications running on a cloud infrastructure”, accessed “through either a thin client interface, such as a web browser (e.g., web-based email), or a program interface.” The same document adds that the consumer “does not manage or control the underlying cloud infrastructure including network, servers, operating systems, storage, or even individual application capabilities.”

That last sentence is the whole deal. You get the application. The vendor keeps everything underneath it.

How SaaS works

Four things happen behind the screen when you use a SaaS product:

1. One copy serves everyone. The vendor runs the software on servers it owns or rents. Most SaaS products are multi-tenant: one running system serves many customers, and each customer sees only its own data. This is how a vendor can charge a few dollars a month and still make money.
2. You reach it over the internet. No installer, no license key on a server in a closet. A browser, a mobile app or an API call is the whole client.
3. Updates arrive for everyone at once. When the vendor ships a new feature or a security fix, every customer gets it, usually without doing anything. The upside is that you are never on an old version. The downside is that you cannot refuse a change you dislike.
4. You pay for access, not for a copy. The usual unit is a price per user per month, billed monthly or yearly. Some products charge by usage (messages sent, gigabytes stored) or by plan tier instead. Stop paying, and access ends.

The five characteristics NIST uses to define cloud services apply to all of this: on-demand self-service, broad network access, resource pooling, rapid elasticity and measured service. In practice that means you can sign up without talking to a salesperson, from any device, share the vendor’s infrastructure with other customers, add 20 users on Monday and remove them on Friday, and pay for what you used.

Who manages what

The question that causes the most trouble in a SaaS contract is not price. It is responsibility. This table is the split that applies to most business SaaS products. Check your own contract and admin settings, because the customer side is larger than most buyers expect.

Area	The vendor	You, the customer
Hosting, servers, network	Runs and pays for it	Nothing
Software updates	Ships them to everyone	Reads the release notes; adjusts training
Platform security	Patches, monitors, certifies (for example SOC 2 or ISO 27001)	Passwords, two-factor settings, who has admin rights
Backups of the platform	Keeps the service recoverable after its own failure	Exporting your own data; restoring a file your user deleted, within the vendor’s trash window
User accounts	Provides the login system	Creates, removes and reviews users; removes leavers
Your data	Stores it and protects it in transit and at rest	Owns it; decides who can see it; deletes it when leaving
Configuration	Provides the settings	Chooses them: sharing defaults, integrations, retention

The pattern: the vendor owns the building, you own what happens inside your apartment. Google, for example, keeps a deleted Workspace user’s data for 20 days and then deletes it permanently unless an admin transferred it first, according to Google’s Admin Help (checked October 2026). That is a customer-side job. More on that split in the guide to Google Workspace as SaaS.

What SaaS costs, with the arithmetic

Example: a 20-person company picks a project management tool priced at $12 per user per month. Compare it with a one-time license for similar software at $300 per user plus a $3,000 server, with the server replaced after three years and a yearly maintenance contract at 20% of the license price. Round numbers, fictional products; the structure is what matters.

Cost line	SaaS at $12 per user per month	One-time license plus server
Year 1	20 x $12 x 12 = $2,880	20 x $300 = $6,000 license; $3,000 server; $1,200 maintenance = $10,200
Year 2	$2,880	$1,200 maintenance
Year 3	$2,880	$1,200 maintenance
Three-year total	$8,640	$12,600
Year 4 onward, per year	$2,880, forever	$1,200, plus a new server when the old one dies

Three lessons sit in that table. First, SaaS wins on cash in the first year because there is no upfront purchase. Second, the lines cross eventually: with a server replaced every three years, the SaaS total passes the license total in year 9 ($25,920 against $25,800). Third, the SaaS column never ends, and the price per user tends to rise over time. Google raised Business Standard from $12 to $14 per user per month in 2025 when it bundled Gemini into the plan, as stated in Google’s announcement of January 15, 2025.

The license column also hides costs the table does not show: the time of the person who patches the server, the downtime when it fails, and the backup you forgot to test. That is the honest reason most small companies choose SaaS. They are not buying software; they are buying the absence of a server room. The SaaS pricing models guide shows how per-seat, usage-based, tiered and freemium prices behave as a company grows.

Ten SaaS products you probably use already

Each of these runs on the vendor’s servers, is used through a browser or an app, and is sold on a recurring basis. Pricing model as shown on each vendor’s pricing page in October 2026.

Product	What it does	How it charges
Google Workspace (Gmail, Drive, Docs)	Email, files, documents	Per user per month, three Business editions
Microsoft 365	Office apps, email, Teams	Per user per month, by plan
Slack	Team messaging	Free plan; paid plans per active user
Zoom	Video meetings	Free plan with a 40-minute limit; paid per license
Notion	Docs and wikis	Free plan; paid per member
Dropbox	File storage and sharing	Free Basic; team plans per user, minimum three users
Salesforce Sales Cloud	CRM	Per user per month, five editions from $25
QuickBooks Online	Accounting	Per company per month, four tiers with user limits
GitHub	Code hosting	Free plan; Team at $4 per user per month; usage charges for compute
Trello	Task boards	Free plan; Standard at $5 per user per month billed annually

Thirty more, grouped by what they do and with a sample monthly bill for a 10-person team, are in SaaS examples: 30 products by category.

Common mistakes

1. Using “cloud” and “SaaS” as synonyms. Cloud is the whole category of renting computing over the internet. NIST splits it into three service models. SaaS is only the finished-application layer; renting a virtual server from AWS is cloud, but it is not SaaS. Why it happens: vendors call everything “cloud”. What to do instead: ask “is this an application, a platform or raw infrastructure?” The guide to SaaS in cloud computing shows the three layers side by side.
2. Assuming the vendor backs up your data for you. The vendor backs up its platform so the service survives its own failures. It does not promise to recover the file your colleague deleted four months ago. Google’s Drive trash keeps files for 30 days, then deletes them forever, per Google Drive Help. Why it happens: “it’s in the cloud” sounds safe. Instead: read the retention settings, turn on the longest window your plan allows, and export what you cannot afford to lose.
3. Forgetting that the subscription never ends. A license is a cost you pay once and amortize. A subscription is a cost that grows with every new hire and every price increase. Why it happens: the first-year number is small. Instead: multiply by three years and by your expected headcount before you compare it with anything else.
4. Leaving the defaults on. The vendor chooses defaults that reduce support tickets, not defaults that protect your data: link sharing on, two-factor optional, one shared admin login. Why it happens: nobody was named as the admin. Instead: name one person, and have them review sharing, authentication and admin roles in the first week.

Go deeper

• SaaS examples: 30 products you probably already use, by category: the products, grouped, with a sample monthly bill.
• SaaS pricing models: per-seat, usage-based, tiered and freemium compared: the same product priced four ways.
• SaaS in cloud computing: how software reaches you over the internet: multi-tenancy, uptime in minutes, and the three cloud models.
• The SaaS business model: how subscription software makes money: why vendors can afford to charge $50 a month.
• Google Workspace as SaaS: editions, admin controls and security explained: the customer side of the responsibility table, on one real product.

Sources

• NIST, Special Publication 800-145, The NIST Definition of Cloud Computing, September 2011.
• Google, The best of Google AI, now included in Workspace Business and Enterprise plans, January 15, 2025.
• Google Admin Help, Delete or remove a user from your organization, and Google Drive Help, Delete and restore files in Google Drive, both checked October 2026.
• Vendor pricing pages linked in the table above, checked October 2026.

In three sentences

SaaS is software that the vendor runs on its own servers and that you use over the internet for a recurring fee instead of installing it. The vendor manages hosting, updates and platform security, while you still own your users, your settings and your data. It costs less up front and more over time, so compare it over at least three years and read the retention settings before you sign.