What is version in IndexedDB?

Question

JavaScript

I started studying indexedDB from books of the 12th year and something didn’t work, I started monitoring in the search engine and realized that a new event was added that checks the version number and only after this check, you can work with the database, but what is the version and what is it the purpose of versioning and why it is so important no where does it say, can anyone clarify these issues?