It's reasonably common to provision a similar but distinct set of resources based on which environment your stack is running in. In your development environment, for example, you may not wish to create an entire fleet of database servers (HA master and read slaves), instead opting for just a single database server. You can achieve this by using conditionals:

• Fn::And
• Fn::Equals
• Fn::If
• Fn::Not
• Fn::Or