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Sreekar Reddy
Sreekar Reddy

Posted on • Originally published at sreekarreddy.com

🎮 Reinforcement Learning Explained Like You're 5

Learning by trial, error, and rewards

Day 73 of 149

👉 Full deep-dive with code examples


The Video Game Analogy

Learning a new video game WITHOUT instructions:

You try things:

  • Jump off cliff → Die → "Don't do that"
  • Hit enemy → Get points → "Do more of that!"
  • Find power-up → Level up → "Remember this path!"

Over time, you get REALLY good!

You learned through trial, error, and rewards.


How It Works

┌─────────────────────────────────────┐
│  Agent (the learner)                │
│         │                           │
│         ▼ Takes action              │
│    Environment (game world)         │
│         │                           │
│         ▼ Gets reward/penalty       │
│  Agent learns and improves          │
└─────────────────────────────────────┘
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The agent tries actions, sees results, and adjusts strategy.


Real Examples

Application Agent Reward
AlphaGo Game player Win the game
Robot arm Controller Pick up object
Self-driving Car AI Avoid collisions
Trading bot Investor Profit

What Makes It Different

Supervised: "Here's the right answer"
Unsupervised: "Find patterns"
Reinforcement: "Figure out what works through experience"

No labeled data. Just a goal and feedback.


The Famous Example: AlphaGo

Google's AlphaGo played millions of games against itself:

  • Win → "That strategy worked!"
  • Lose → "Don't do that again"

Eventually beat the world champion at Go!


In One Sentence

Reinforcement learning trains AI through trial and error, using rewards to reinforce successful actions.


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