Walmart and Food Supply Chain

  1. What's the Problem Walmart Faced?

    1. Imagine you’re eating a salad and suddenly people start getting sick from bad lettuce.
    2. Walmart sells lots of food, like fruits, vegetables, and meat. But sometimes, one of the foods might be bad—like it has germs that make people sick.
    3. The big problem is:
      1. Walmart didn’t know exactly where that food came from.
      2. It took weeks to find the farm where that bad food started.
      3. That meant millions of people were at risk because Walmart couldn’t stop selling the bad food fast enough.
    4. They needed a better, faster, and more transparent way to track food.

  2. How Blockchain Solves It

    1. Think of the Supply Chain Like a Treasure Map
      1. When food moves from farm → truck → factory → store → your home, it’s like it’s going on a treasure hunt journey.
      2. Before blockchain:
        1. Everyone wrote their part of the journey in different notebooks.
        2. Some people forgot to write things.
        3. Some lied or changed the information.
        4. No one could see the full map!
      3. So if someone got sick, Walmart had to look through a bunch of messy notebooks to find the bad food’s starting point.
    2. Now Enter Blockchain: The Magic Notebook
      1. Walmart started using a blockchain system (with IBM Food Trust) that works like a magic notebook that:
        1. Everyone can write in, but no one can erase or cheat.
        2. Each time food moves (farm → truck → factory → store), a new page is added.
        3. All the pages are linked together—this is the "chain" in blockchain.
    3. Key Principles of Blockchain in Action
      1. Let’s see how blockchain helped Walmart fix the problem using its 3 superpowers:
      2. Transparency – Everyone Can See the Truth
        1. Every time someone touches the food (like a farmer or truck driver), they write the time, place, and condition into the blockchain.
        2. Walmart, suppliers, and health inspectors can see the whole journey of the food—like a Google Maps for vegetables!
        3. So if someone gets sick, they can find exactly which farm the lettuce came from in seconds, not weeks.
      3. Immutability – No Erasing or Cheating
        1. Once someone writes a page in the blockchain notebook, they can’t erase it.
        2. That means a dishonest supplier can’t hide that they didn't wash the lettuce properly.
        3. Everyone is forced to be honest.
      4. Decentralization – No One Owns It All
        1. The blockchain isn't controlled by just Walmart. Multiple people share it: farmers, truckers, packagers, and stores.
        2. That means no single person can secretly change the information.
        3. It’s like everyone shares one notebook, and everyone trusts it because no one can cheat.

  3. Real Result at Walmart

    1. Before blockchain:
      1. It took 7 days to trace food back to its source.
    2. After blockchain:
      1. It takes just 2.2 seconds to know exactly which farm the food came from!
    3. This helps Walmart:
      1. Remove only the bad food from the shelves (not everything).
      2. Act faster to keep people safe.
      3. Save money by not throwing away good food.

  4. In Simple Words: Why This Matters

    1. Think of blockchain like a magic notebook that tells the truth and never forgets.
    2. Walmart uses it to track every move of your food, so you don’t get sick.
    3. It makes the food world safer, faster, and smarter.

  5. In Essence

    Feature Old Way (No Blockchain) New Way (With Blockchain)
    Food Tracking Time 7 days 2.2 seconds
    Trust in Info Could be wrong or faked 100% secure and unchangeable
    Problem Solving Slow and unclear Fast and accurate
    Control One company or messy systems Shared across everyone

Ethereum and Smart Contracts

  1. What's the Problem Ethereum Solves?

    1. Let’s say you want to:
      1. Hire a graphic designer online.
      2. Or buy a digital game from someone on the internet.
      3. Or rent a car from a stranger using an app.
    2. You send them the money first…
    3. But what if they don’t do their part?
      1. The designer runs away.
      2. The game never gets sent.
      3. The car never arrives.
    4. You feel cheated.
    5. You’d usually need a middleman like a lawyer, bank, or website to make sure both sides play fair.
    6. But middlemen:

  2. Enter Ethereum: The World’s Computer with Smart Contracts

  3. Real-World Example: NFTs and Artists