Monthly Recurring Revenue (MRR) is a crucial metric in Software as a Service (SaaS) businesses, representing the predictable income from subscriptions. It plays a significant role in attracting venture capital and growth equity firms and helps gauge financial stability while monitoring for signs of stagnation. MRR can be calculated by adding up recurring revenue or using Average Revenue Per User (ARPU) for precise monthly tracking. To fuel business growth, assess MRR against other metrics like Customer Acquisition Cost (CAC) and Lifetime Value (LTV). Implementing growth tactics such as refining pricing, enhancing product features, and leveraging usage-based billing software can also help boost MRR.