HTTP/HTTPS deeply — HTTP (Hypertext Transfer Protocol) solves the framing and semantic problem by standardizing request-response structures, caching metadata, content negotiation, and status codes.
TCP/IP basics — At the lowest physical layer, computer networks transport raw pulses of light, electricity, or radio waves. Internet Protocol (IP) operates above this layer to handle logical…
DNS — The Domain Name System (DNS) solves these problems by providing a globally distributed, hierarchical, eventually-consistent lookup mechanism that translates human-readable domain…
TLS/SSL — When two machines communicate across a public network (such as the Internet), their raw IP packets pass through multiple intermediate hops—routers, switches, internet service…
HTTP/1.1 vs HTTP/2 vs HTTP/3 — In production, you’ll see these symptoms as slow page loads, high error rates, and resource exhaustion on the load balancer or application server.
REST API Design — RESTful design is the backbone of most modern web services: Twitter, GitHub, Stripe, and many internal microservices use it.
RPC / gRPC — gRPC (Google Remote Procedure Call) addresses all of the above by providing a binary, type‑safe, streaming RPC framework that runs over HTTP/2, with automatic code generation and…
WebSockets — WebSockets are the de‑facto standard for any backend that needs to push data to clients instantly and maintain a persistent, low‑overhead channel.
Server‑Sent Events (SSE) — Real‑time data from server to client Many web apps need to push updates to the browser (chat, live scores, dashboards) without the client constantly polling the server.
Request/response lifecycle — Just as a letter travels from sender → sorting → clerk → processing → return, an HTTP request travels through a series of deterministic steps before a response is sent back.
Cookies, sessions, tokens — When a user interacts with a web application, the server needs a way to remember that the user is the same across multiple HTTP requests. HTTP is stateless, so each request is…
CORS — Motivation Web browsers enforce a same‑origin policy (SOP) to protect users from malicious cross‑site requests. Under SOP, a script running on https://app.example.com can only…
Idempotency — Motivation When a client sends a request that changes state (e.g., create an order, charge a card, update a profile), the client often wants to be sure that the operation is…
Stateless vs Stateful Services — In production, most backends aim to be stateless so that any instance can serve any request. When state is required, it is externalized (database, cache, message queue) so that…
Serialization / deserialization — Why it matters Without proper serialization you risk data corruption, security holes (e.g., code injection via eval), and brittle APIs that break when the data shape changes.
API versioning — Motivation When a backend exposes an HTTP API, clients (web, mobile, third‑party services) depend on the shape of the data and the semantics of the endpoints. As the product…
Pagination — Imagine a library with a catalog of 10 000 books. You want to find all books by a particular author. Instead of handing you the entire catalog, the librarian gives you a page of…
Filtering / Sorting — At scale, filtering/sorting becomes a bottleneck and a cost driver.
Rate limiting — Why it matters Rate limiting protects the service’s availability, performance, and cost while also providing a first line of defense against abuse.