Learn the foundations,
one X at a time.
A visual, interactive companion for foundational topics that are usually explained with walls of text. Every lesson is hands-on — you click, drag, and watch the concept happen instead of just reading about it.
Subjects
Fundamental of Database
ACID, B-Trees, replication, sharding, WAL, isolation levels, and how SQL queries actually run — explained through interactive widgets you can poke at.
Fundamental of Internet
How bytes get from one machine to another. IP, TCP, UDP, DNS, TLS handshakes, packet flow, latency, BGP routing — the plumbing under every URL.
Fundamental of Backend
HTTP verbs, status codes, headers, cookies, REST, request lifecycles, proxies, load balancers, caching, rate limiting — what backends actually do with the requests they receive.
Fundamental of Kafka
Topics, partitions, consumer groups, offsets, log compaction — learn the streaming model by watching events flow.
Fundamental of Distributed Systems
Consensus (Raft, Paxos), the CAP theorem, leader election, vector clocks, gossip — watch nodes argue, vote, and recover from partitions in real time.
Fundamental of Cryptography
Hashing, symmetric vs asymmetric, digital signatures, key exchange, certificates — animated step-by-step so you understand what's really inside a TLS handshake.
Fundamental of Operating Systems
Processes vs threads, the scheduler, virtual memory, paging, syscalls, file descriptors — the layer beneath your code that decides whether it's fast.
Fundamental of Computer Architecture
CPU pipelines, branch prediction, cache lines, the memory hierarchy, MMU, SIMD — why two semantically identical programs run at 10× different speeds.
Fundamental of Light
Reflection, refraction, diffraction, wavelengths, color — the physics of light through interactive optical experiments.
Fundamental of Solar Cell
How a photon becomes electricity. Bandgaps, electron-hole pairs, the P-N junction, efficiency limits — interactive physics behind every panel on every rooftop.
Why visual?
A picture of a B-Tree splitting is worth more than three paragraphs of prose, and an animation of a transaction rolling back beats any bullet list. This site is built for learners who want to see ideas move, not just read about them.
Each subject is a self-contained module. Today only Database is shipped — more subjects will follow.