AWS Reserved Instances are a cost-saving option for businesses that need to reserve capacity ahead of time, offering discounts on hourly rates and predictable pricing. They come in different types, including EC2, RDS, and RI marketplace options, each with varying discounts and billing requirements. Businesses can benefit from Reserved Instances by achieving high returns on investment, reliability, and outage protection. To manage AWS Reserved Instances effectively, tools like Archera offer features such as tagging and attribution, dynamic use planning, machine learning for purchase and renewal decisions, automated resource management, cost-anomaly identification, and guaranteed reserved instance buy-back. These tools can help businesses optimize their commitments, avoid wasting spend, and make informed purchasing decisions.