Composite Pattern Explained: Files, Folders, and Trees
Show notes for the Composite Pattern video — when to use it, real-world examples (file systems, the DOM, React trees), and a code-free mental model.
Engineering blog
Written deep-dives and companion notes to the LearnwithManoj YouTube channel.
Bridge Pattern Explained - Kill the Class Explosion | 10/25
Bridge Pattern - the fix for class hierarchies that explode into `RedCircle`, `BlueCircle`, `RedSquare`, `BlueSquare`.
Adapter Pattern Explained - The USB Adapter of Code | 9/25
Adapter Pattern - the software version of a USB-C to USB-A dongle. When two pieces of code need to talk to each other but their interfaces don't match, Adapter…
Securing AI Agents from Doing Bad Things
Show notes for AI Explained Part 31 — sandboxing, permission scoping, instruction hierarchy, and the metrics that tell you whether your agent is safe to ship.
AI Explained: Finally Understand AI Errors & Human-in-the-Loop (HITL) (Part 30)
Feeling overwhelmed by the fear of AI making huge mistakes? In this video, we break it down into simple pieces.
AI Explained: Semantic Caching & State Management for AI Agents (Part 29)
Feeling overwhelmed by high AI API costs and latency? In this video, we break it down into simple pieces.
AI Explained: Short-Term vs Long-Term AI Memory Demystified (Part 28)
Feeling overwhelmed by the different layers of AI memory? In this video, we break it down into simple pieces.
AI Explained: Finally Understand How AI Agents Remember You (Part 27)
Feeling overwhelmed by memory and state tracking? In this video, we break it down into simple pieces.
AI Explained: Multi-Agent AI Systems for Complete Beginners (Part 26)
Feeling overwhelmed by the idea of communicating AIs? In this video, we break it down into simple pieces.
AI Explained: How AI Uses Tools - ReAct Loop & Tool Use Demystified (Part 25)
Feeling overwhelmed by APIs and AI Tool Integration? In this video, we break it down into simple pieces.
AI Explained: Finally Understand Autonomous AI Agents & Agentic RAG (Part 24)
Feeling overwhelmed by the hype around "AI Agents"? This video is your ultimate guide to finally understanding AI Agents and Agentic RAG, even if you're completely new…
Singleton Pattern Explained - Anti-Pattern or Essential? | 8/25
Singleton Pattern - the most controversial design pattern in software. Half the developers call it an anti-pattern, the other half use it every day. So who's right?
Prototype Pattern - Clone Objects Instead of Rebuilding | 7/25
Prototype Pattern - when creating an object from scratch is expensive, clone an existing one instead. This is also where shallow-copy vs deep-copy bugs come from.
Builder Pattern - Stop Writing Huge Constructors | 6/25
Builder Pattern - stop writing constructors with 12 parameters. This is the cleanest way to construct complex objects step by step.
Abstract Factory Pattern - The 'Factory of Factories' Explained | 5/25
Abstract Factory Pattern explained with the matching-showroom analogy - the creational pattern for when you need to produce entire families of related objects together.
Factory Method Pattern vs Simple Factory Pattern - Finally Explained | 4/25
Factory Method Pattern vs Simple Factory Pattern - the exact difference most tutorials never make clear, and a classic software engineering interview question.
AI Masterclass Part 23: GraphRAG Explained for Complete Beginners
Feeling overwhelmed by complex AI data architectures? In this video, we break it down into simple pieces.
AI Masterclass Part 22: Finally Understand AI Reranking
Why is your AI missing the context? In this video, we break down Reranking. We show you the secret 2nd stage of the search pipeline that perfectly orders results from…
AI Masterclass Part 21: Hybrid Search for People Who Hate Math
Feeling overwhelmed by your AI giving you bad search results? In this video, we break down Hybrid Search—the ultimate strategy of combining exact keywords with deep…
AI Masterclass Part 20: Vector Databases for People Who Hate Math
Feeling overwhelmed by Vector Databases and SQL? In this video, we break it down into simple pieces.
AI Masterclass Part 19: Data Chunking for RAG Explained Simply
Feeling overwhelmed by getting your data ready for AI? In this video, we break it down into simple pieces.
AI Masterclass Part 18: Finally Understand RAG
Feeling overwhelmed by the term "RAG"? In this video, we break it down into simple pieces.
AI Masterclass Part 17: Hack Proofing Your AI | Prompt Injection
Feeling overwhelmed by AI security risks? In this video, we break it down into simple pieces.
AI Masterclass Part 16: AI Context Limits Explained Simply
Feeling overwhelmed when your AI forgets what you said 20 minutes ago? In this video, we break it down into simple pieces.
AI Masterclass Part 15: How AI Reasons | Chain & Tree of Thought
Feeling overwhelmed by how AIs solve complex math or logic puzzles? In this video, we break it down into simple pieces.
How to Crack Any System Design Interview — Full Beginner's Guide
Most candidates fail system design interviews not because they lack knowledge — but because they don't have a clear framework to structure their thinking.
AI Masterclass Part 14: Finally Understand Few-Shot AI Prompting
Feeling overwhelmed by advanced AI prompting techniques? In this video, we break it down into simple pieces.
AI Masterclass Part 13: Prompt Engineering for Complete Beginners
Feeling overwhelmed by bad AI responses? In this video, we break it down into simple pieces.
AI Masterclass Part 12: AI Distillation & Synthetic Data Explained
Feeling overwhelmed by how complex AIs stay small enough to run on phones? In this video, we break it down into simple pieces.
AI Masterclass Part 11: AI Alignment for Complete Beginners | RLHF
Feeling overwhelmed by AI safety terminology? In this video, we break it down into simple pieces.
AI Masterclass Part 10: Understand LoRA & Local AI Shrinking Models
Feeling overwhelmed by the hardware requirements of AI? In this video, we break it down into simple pieces.
AI Masterclass Part 9: Fine Tuning AI for People Who Hate Math
Feeling overwhelmed by the term "Fine-Tuning"? In this video, we break it down into simple pieces.
AI Masterclass Part 8: Finally Understand How AI is Trained
Feeling overwhelmed by how tech giants actually build ChatGPT? In this video, we break it down into simple pieces.
AI Masterclass Part 7: The Truth About AI Pricing and Costs
Feeling overwhelmed by confusing API pricing tiers? In this video, we break it down into simple pieces.
AI Masterclass Part 6: Why AI Can Be Slow? | Inference
Feeling overwhelmed by latency complaints in your AI app? In this video, we break it down into simple pieces.
AI Masterclass Part 5: Choosing an AI Model for Complete Beginners
Feeling overwhelmed by the hundreds of AI models launching every week? In this video, we break it down into simple pieces.
AI Masterclass Part 4: Finally Understand AI Memory | Embeddings
Feeling overwhelmed by high-dimensional matrices and embeddings? In this video, we break it down into simple pieces.
AI Explained: Finally Understand the Magic of Transformers | Attention (Part 3)
Feeling overwhelmed by Transformer architecture diagrams? In this video, we break it down into simple pieces.
AI Explained: Tokenization for Non-Math People (Part 2)
Ever wonder why AI makes simple math or spelling mistakes? This video demystifies tokenization, breaking down how AI cuts up English words into puzzle pieces.
AI Explained: Finally Understand How AI Works - No Code (Part 1)
Unlock the secrets of AI in this masterclass! Part 1 simplifies how AI works, especially Large Language Models like ChatGPT, without any code.
Design a Scalable System from Scratch — Full Blueprint (System Design #15)
You've learned the pieces. Now let's put them all together and design a real scalable system from scratch — the way it's done in interviews and in production.
Monolith vs Microservices - Which Architecture Should You Choose? (System
Microservices are everywhere - but are they always the right choice? Spoiler: most teams adopt them too early, and it costs them.
REST vs WebSockets vs SSE - When to Use Each (System Design #13)
Building a chat app? A live dashboard? A REST API? Each needs a completely different communication model - and picking the wrong one is a costly mistake.
Consistent Hashing, Replication & Redundancy - How Distributed Systems Scale
What happens when you add or remove a server from a distributed system? Without consistent hashing, the answer is chaos.
CAP Theorem Explained in 6 Minutes (System Design Interview #11)
CAP Theorem is one of the most misunderstood concepts in distributed systems - and one of the most asked about in FAANG interviews. Let's fix that.
Database Sharding & Indexing - How Big Apps Scale Their Data (System Design #10)
When your database has 500 million rows, queries don't just slow down - they can grind your entire app to a halt. Here's how the biggest systems solve it.
Key-Value, Document, Wide-Column, Graph - 4 NoSQL Types Explained (System
NoSQL is not one thing - it's four completely different data models. Choosing the wrong one is just as bad as choosing SQL when you shouldn't.
SQL vs NoSQL - How to Choose the Right Database (System Design #8)
Picking the wrong database early can haunt your system for years. SQL or NoSQL - here's how to make the right call every time.
FIFO, LIFO, LRU, MRU, LFU - Cache Eviction Policies Explained Simply (System
Your cache is full. Something has to go. But which item do you remove - and does it even matter? The answer can make or break your app's performance.
Write-Through vs Write-Back Cache - Which Should You Use? (System Design #6)
Caching makes systems fast - but it also introduces one of the hardest problems in computer science: keeping your cache and database in sync.
Caching Explained - How Apps Stay Fast Under Heavy Load (System Design #5)
Without caching, even the fastest databases would crumble under real-world traffic. It's one of the most powerful performance tools in any engineer's toolkit.
How Load Balancing Works - Round Robin, Least Connections & More (System
How do systems like Google and Amazon handle millions of users simultaneously without crashing a single server? Load balancing is the answer.
Vertical Scaling vs Horizontal Scaling - What's the Difference? (System Design
Your app is getting more traffic. Do you buy a bigger server - or add more servers? This decision can make or break your system.
Scalability vs Reliability vs Availability - Simply Explained (System Design #2)
What separates a good software system from a bad one? It comes down to 5 key characteristics - and most engineers can't clearly explain all of them.
What Is System Design? A Beginner's Roadmap to Scaling Real Apps
A beginner's roadmap to system design: scalability, availability, load balancing, caching, and monolith vs microservices — with the companion YouTube video.