Which AWS service will allow a user to set custom cost and usage limits, and will alert when the thresholds are exceeded?

Explanations:

AWS Organizations is primarily used for managing multiple AWS accounts and applying policies, not for setting cost limits or alerts.

AWS Budgets allows users to set custom cost and usage limits and provides alerts when thresholds are exceeded, making it the correct choice.

Cost Explorer is used for analyzing costs and usage patterns over time but does not provide the functionality to set custom alerts for thresholds.

AWS Trusted Advisor offers recommendations for best practices in AWS usage, but it does not provide the capability to set custom cost limits or alerts.