> For the complete documentation index, see [llms.txt](https://docs.rulecube.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.rulecube.com/v2.5/how-to-guides/ruleset-development/generate-alerts.md).
# Generate Alerts
## Introduction
This guide explains how to create an alert for a ruleset.
**Alerts** are a special type of rule that allows you to check whether the input or a calculated result meets business rule conditions. For example, if the age of a new subscriber must be 18 or older, you can have an alert checking the age and signaling a message if the applicant is too young.
## Procedure
Let's work the '18 or older'-rule out into an alert. To do so, you'll first create a rule that calculates the age and then an alert that checks the age:
1. Create a ruleset named `AgeCheck`.
2. Create an input named `DateOfBirth` with **Type** = `date`.
3. Click the **+** sign behind **Rules** from the left menu.\
↳ The **Rule details** page opens.
4. In the **Name** field, enter the name for the rule. For example, `SubscriberAge`.
5. In the **Expression** field, enter the following code to calculate the age:
```javascript
AGE(DateOfBirth)
```
6. Click **Save**.
7. Click the **+** sign behind **Rules** again to create the alert.
8. In the **Name** field, enter the name for the rule. For example, `AgeCheck`.
9. In the **Expression** field, enter the following code to calculate the age:
```javascript
SubscriberAge < 18
```
\
↳ This code refers to and uses (the result of) the `SubscriberAge` rule.
10. Select the **Generate alerts** checkbox.\
↳ Rulecube adds the **Alert settings** section to the page.
11. In the **Alert type** list, select **Error**.
12. In the **Title** field, enter `Too young to subscribe`.
13. Select the **Enable expression** checkbox.
14. In the **Message** field, enter the following expression:
```javascript
`The subscriber is ${SubscriberAge} years old and should be 18 or older.`
```
\
Notice the backticks as the expression is template literal.
15. Click **Save** followed by **Try it out!** to open the sandbox for the ruleset.
16. In the DateOfBirth input, enter a birthdate younger than 18.
17. Click **▸Execute.** \
↳ The **Results** section shows an alert like this:
18. Now, try the ruleset with a valid birthdate.
---
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