Tech in Diagrams

What is a Server?

A server is a computer whose job is to answer requests from other computers, continuously.

Beginner 4 min IT Fundamentals
Inside the machine that answers
  • Request / response
  • Processing
  • Data call
BrowserGET /ordersSends a request, waitsMobile appPOST /ordersSends a request, waitsAnother serviceMachine-to-machineSends a request, waitsNETWORKAddressedto a porthost:443Many clients,one addressINGRESSListening port:443 OPENAccepts the connectionCONCURRENCYQueue · workers3 in flight, 1 waitingPROCESSINGApplicationlogicValidates, decides,builds the responseSERVER HARDWARE — CAPACITY, NOT THE ROLEData storeRead and write the statethe response is built fromSELECT · INSERTIF IT STOPS LISTENINGService unavailableNo process on the port meansthe request simply fails.no responseResponseback to the same clientPhysical machineRack hardwareVirtual machineShared hostContainerShared kernelCloud instanceRented capacity
The listening service, not the box, is what makes this a server: it accepts a connection, works through a short queue of requests, reads or writes data, and answers the client that asked.

Hover a client, the port, the queue, the hardware layer or the data store to isolate its path; click any component for a short explanation.

Next conceptWhat is a Database?A database stores structured data and answers queries reliably, even with many users writing at once.