They use three mechanisms:
1. Advertising. “Just buy this product and you will be happy”. Or something like that.
2. Planned Obsolescence – things are made to break. Remember the days when a TV lasted for 20 years? Not anymore because they want you to buy a new one after 3 years (if you are lucky that it lasts that long!)
3. Fashion. Now we even throw away perfectly good stuff just because it is not in fashion anymore.
Learn more in this great video: The Story of Stuff
Next: Where does the money go?