Reqflow teaches by running real artifacts: not slides. Pick a path below, or skim the vocab if system-design words feel fuzzy.
A short route that won't leave you lost.
Optional skim, enough to feel at home in the diagrams.
The thing making the request, usually a browser or phone app.
A program that listens for requests and sends back responses.
Where data lives long-term. Survives restarts.
Fast temporary storage for things you'll look up again soon. Throws stuff away when full.
A line of pending work, processed in order. Lets a slow worker handle bursts from a fast producer.
A copy of the data on another machine, kept in sync with the primary.
One slice of a dataset that's been split across many machines. Each shard handles its slice independently.
The front door to your system. Every request hits it first, then it routes to the right backend.