"I am familiar with all of the terms you mention. To start, I would define the scalability of a product as the ability to grow it without any impact on its production environment. In other words, maintaining peak performance of the product even while encountering high growth and ensuring that the customers aren't affected at all. When it comes to securability, this refers to meeting regulatory requirements and handling compliance reporting, as well as managing things like encryption, archiving, and authentication. It also means being prepared for certain scenarios like high-availability (HA) and disaster recovery (DR). Billability, on the other hand, is a term that refers to a system being able to handle various billing options whether they be based on subscribers, usage, or transactions. This system needs to be easily adjustable and offer simplified reporting of usage and other metrics. Finally, reliability means that performance and uptime need to be working at peak levels and there should be backup strategies in place if needed."