Database index

A database index is like a list that helps computers find the information you're looking for very quickly. Imagine having a huge library filled with books. If you wanted to find a particular book you'd need to look through all of the books alphabetically, which would take a long time. But if the library had an index that listed all of the books and the page they were on, you could look up the book and find it much quicker. That's what a database index does - it helps computers find the information they need much faster.