credit cards 

INTRODUCTION : In the  daily life we use many elements containing magnetisim. I will talk about barcodes and of credit cards . 

EXPLANATION : When you go to a store to buy something this product has a barcode , unique in world , a reading machine wich says the product price is and some information about the product. 

The credit cards have magnetic strips , that are used for read the information .  Credit cards are used to pay without cash.