We created a simple alarm and learned how to trigger it. Some of the important things to remember regarding CloudWatch alarms include the following:

• The alarm period should be equal to or greater than the metric frequency.
• The state of the alarm should change (for example, OK to ALARM) for the alarm to trigger an action. 
• The alarm and its actions must be in the same region.
• We can create an alarm before we create the metric. The alarm stays in the INSUFFICIENT_DATA state until the metric is available with data.

In this recipe, we created an alarm from only AWS CLI. However, if you have fully understood this recipe, then you can do the same easily with Management Console.