A plain-language, complete guide to why horizontal scaling has become the default for large systems: the big idea, a quick recap of vertical vs horizontal, a short history of how we got here, and seven concrete reasons the world’s busiest systems keep choosing to grow sideways rather than upward (the…

A plain-language, complete guide to stateless services: what they really are, a short history from HTTP’s early days to modern cloud computing, what “state” actually means (session, application, connection, persistent), how a stateless request-response cycle works, the differences between cookies, server sessions, and JWT tokens, a side-by-side comparison of stateless…

A plain-language, complete guide to caching in software design: what caching really is, a short history of the idea from 1960s hardware caches to modern CDNs, how it actually works (hits, misses, hit rate, cold starts), the four main types of caches (application, distributed, global, CDN/edge), the four main read/write…

A plain-language, complete guide to why architects prefer stateless services when designing for scale: what state actually means, a short history of the idea from the earliest web, stateless vs stateful side by side, the four core reasons statelessness wins (effortless scaling, surviving failure, simpler deployments, easier testing), why it…

A plain-language, complete guide to cache invalidation: what it really is, a short history of the famous problem, how it actually works (passive vs active), why it is considered so hard, the crucial difference between invalidation and eviction, the four broad types (time-based, event-based, command-based, group-based), common techniques (TTL, purge,…

A plain-language, complete guide to why cache invalidation is considered one of computing’s hardest problems: what a cache really is, what “invalidation” actually means, a short history of the famous joke, why we cache in the first place, the four core reasons the problem is so hard (too many copies,…

A plain-language, complete guide to Content Delivery Networks: what a CDN really is, a short history from the 1990s to today, how it actually works with DNS and Anycast routing, the building blocks (PoPs, edge servers, origin, traffic director), origin pull vs origin push, how to spot a CDN at…

A plain-language, complete guide to throughput: what it really is, a short history of the idea from factories to fibre-optic cables to Kanban boards, how throughput is measured in networking, how it differs from bandwidth and from latency, what affects it, how it shows up in project management, how it…

A plain-language, complete guide to latency: what it really means, a short history of the idea, how latency is measured (with percentiles), how it differs from throughput and bandwidth, the four causes (propagation, transmission, processing, queuing), latency across connection types (fibre, Wi-Fi, mobile, copper, satellite), the different kinds of latency…

A plain-language, complete guide to the difference between latency and throughput: what each one really is, a short history of the distinction, how each is measured, what shapes them, how they interact, the surprising math of utilization and the cliff edge queueing theory predicts, the TCP vs UDP trade-off, where…