I’ve chatted with a few founders who proudly share their recurring revenue numbers to show how their businesses are growing. But their revenue isn’t recurring. They aren’t trying to mislead—they often don’t know what “recurring revenue” means.

Revenue is recurring when the customer has agreed to pay a predetermined amount over a predetermined time. Subscription revenue is a great example. A customer signs an annual contract for $1,200 and agrees to pay $100 per month on the 1st of every month. Alternatively, the customer could give you the entire $1,200 up front to gain access to your solution for the year. Either way, the duration is a calendar year and the amount paid is $1,200.

Another wrinkle on subscriptions is monthly software with no contract. Let’s say a customer signs up for a SaaS tool such as Calendly, agrees to pay $10 per month, and can cancel anytime. This is still subscription revenue. It’s a one-month subscription that auto renews at the end of every month unless the customer cancels. The duration is a month, and the agreed-upon amount is $10.

The great thing about recurring-revenue businesses is that they start with a known amount of monthly revenue that customers have agreed to. Customers must notify the company when they plan to stop paying, which gives the company prior knowledge of when revenue from a customer will decline. This revenue base makes planning and forecasting more accurate for small and large companies.

If revenue isn’t recurring, it’s likely transactional. Transactional revenue doesn’t involve predetermined amounts, and the frequency of payments varies. Grocery stores are great examples of transactional-revenue businesses. Customers can walk in whenever they want and buy as much or as little as they want. There’s no commitment between the store and the customer. Every month, the store starts with a revenue base of zero. Customers don’t have an obligation to notify the store if they’ll stop shopping there. This can make planning and forecasting difficult until the company has a large customer base.

If you’re building a transactional-revenue business and want to demonstrate that revenue is growing, don’t use terms like “recurring revenue” or “annual recurring revenue.” Consider something like “revenue run rate” or “annual revenue run rate” if it makes sense for your business.