Introduction to Caching

An online store has one very popular product. Its page is viewed 10,000 times every minute. Each view runs the same database query to load the product's name, price, and description, and each query takes 50 ms.

The product details almost never change. But the database repeats the same work 10,000 times a minute, and it slows down for every other request too.

The fix is to keep a copy of the answer somewhere much faster and reuse it. This lesson explains what that fast storage is, how it works, the terms used to describe it, and what it costs.