- goal is to show as many signals as possible: can you design a scalable system? Questions for understanding exact requirements: - what specific features are we going to build - how many users does the product have? - how fast does the company anticipate to scale up? what are the anticipated scales in 3 months, 6 months, and a year? - what's the company's tech stack? what existing services might you leverage to simplify the design? - goal: get interviewer to agree with design, collaborate with them - afterwards you can dive deeper - finally you can wrap up by talking through bottlenecks and potential improvements