System Design › Fundamentals
Database Indexing: How One Line Makes Queries 1000x Faster
Database indexing explained from scratch — full table scans vs index lookups, how B-trees work, what to index (WHERE, JOIN, ORDER BY), composite indexes and the left-most rule, the read-vs-write trade-off, covering indexes, and EXPLAIN.
Java
Java Date and Time API: Working with LocalDate and LocalDateTime
Learn the modern Java Date & Time API (java.time) — LocalDate, LocalTime, LocalDateTime, date maths, comparing, formatting with DateTimeFormatter, and measuring gaps.
Java
File I/O in Java: Reading and Writing Files the Modern Way
Learn file input/output in Java with the modern Files and Path API — read and write text, handle IOException, and use try-with-resources to close files safely.
System Design › Fundamentals
SQL vs NoSQL: How to Choose the Right Database (With Examples)
SQL vs NoSQL explained without the hype — how relational tables and ACID differ from the four NoSQL types (document, key-value, wide-column, graph), when to use each based on your data, and why real systems mix both (polyglot persistence).
Java
Multithreading in Java: Running Tasks in Parallel (Beginner Guide)
Learn multithreading in Java gently — what threads are, how to start one, the danger of race conditions with shared data, synchronized, and modern thread pools.
System Design › Fundamentals
Caching Strategies: How to Make Systems Fast (Cache-Aside, Write-Through & More)
Caching explained from scratch — cache hits and misses, where caches live, the four caching patterns (cache-aside, write-through, write-back, write-around), eviction (LRU, TTL), and the hard problems: staleness, invalidation and the thundering herd.
Java
Optional in Java: A Safer Way to Handle Missing Values
Learn Java Optional to avoid NullPointerExceptions — what it is, how to create one, and how to use orElse, ifPresent and isPresent to handle missing values cleanly.
Java
The Streams API in Java: Process Collections the Modern Way
Learn the Java Streams API — filter, map, sorted, collect and more. Turn bulky loops into clean, readable data pipelines, with clear beginner examples.
System Design › Fundamentals
Load Balancing Explained: How One URL Serves Millions of Users
How a load balancer spreads traffic across many servers so no single one is overwhelmed and none is a single point of failure. Covers round robin vs least connections, health checks, sticky sessions, L4 vs L7, and load balancer redundancy — with a clear diagram.
Java
Lambdas and Functional Interfaces in Java Explained
Learn Java lambdas the easy way — pass code as a value, understand functional interfaces, lambda syntax, and built-ins like Predicate, Function, Consumer and Supplier.
System Design › Fundamentals
Scalability Explained: Vertical vs Horizontal Scaling (With Examples)
Scalability made simple — the difference between scaling up (a bigger machine) and scaling out (more machines), why statelessness is the golden rule, when to use each, auto-scaling, and how to answer 'how would you scale this?' in an interview.
Java
Immutability in Java: Building Objects That Never Change
Learn immutability in Java — what immutable objects are, why they are safer and thread-safe, and how to build your own immutable class step by step, with records as the modern shortcut.