Kafka Core Vocabulary — Broker, Topic, Partition, Offset
Follow one OrderPlaced event from write to read — broker, topic, partition, and offset in plain English, with interactives.
Why Kafka Exists
What problem Kafka solves — durable logs, decoupled services, and replay — and when a simple HTTP call is still the right answer.
Why Go Doesn't Have While Loops
if, switch, for, break, continue, labels, and defer — and why Go replaced while, do-while, and foreach with a single loop word.
Why Go Doesn't Let Variables Stay Uninitialized
Variables, types, constants, zero values, and := — explained simply. Why every Go variable starts with a real value, and how that stops a whole class of bugs.
Why Google Invented Go Instead of Improving C++
A case study of the problems that created Go — compile time, dependency hell, memory safety, concurrency, and why Go intentionally left features out.
Why Simple Code Beats Clever Code
The Go philosophy — readability, explicit code, zero values, composition, and small interfaces — and why boring code often scales better than smart code.
Stacks & Queues — Complete Guide with Interactive Walkthroughs
Master LIFO stacks, FIFO queues, and monotonic deques — parentheses matching, adjacent duplicates, recent calls, daily temperatures, and sliding window maximum. Animations included.
Linked Lists — Complete Guide with Interactive Walkthroughs
Master linked list mechanics, fast and slow pointers, and in-place reversal — insert/delete, cycle detection, k-th from end, and swap pairs without cheating into an array. Animations included.
Binary Search — Complete Guide with Interactive Walkthroughs
Master binary search on sorted arrays and answer spaces — classic templates, lower/upper bounds, 2D matrix tricks, and O(n log k) feasibility checks. Animations included.
Hashing — Complete Guide with Interactive Walkthroughs
Master hash maps and sets for O(1) lookups — existence checks, frequency counting, prefix + frequency patterns, and grouping. The most important data structure in interview prep. Animations included.
Prefix Sum — Complete Guide with Interactive Walkthroughs
Master prefix sums for O(1) subarray range queries — build the array, answer queries in constant time, split arrays in one pass, and optimize to O(1) space. Step-through animations included.
Two Pointers — Complete Guide with Interactive Walkthroughs
Master the two pointers technique for arrays and strings — opposite ends, merge walk, palindrome checks, two sum on sorted input, and subsequence matching. Step-through animations included.
Sliding Window Technique — Complete Reference with Animations
A friendly, step-by-step guide to sliding windows — from your first two-pointer problem to monotonic deques, production rate limiters, and the at-most-K trick. Interactive animations included.
Is Git Confusing? A Git Crash Course to Get You Started!
An interactive Git crash course — step-through animations for daily workflows, branching strategies you can play through, and a scenario picker for everyday situations.
JavaScript Variables and Data Types
const, let, typeof, primitives, null vs undefined — the parts of JavaScript that show up in every file, explained without the textbook tone.