Prototype Design Pattern GOF In JS

I'm trying to learn about design patterns in JavaScript, specifically the Gang of Four design patterns. I'm familiar with some of the patterns, but I'm not sure about the Prototype pattern. Can anyone explain the Prototype design pattern in JavaScript and give an example of when it would be useful to use in a project?

Would it really be more expensive in JS not using Prototype Pattern because JS is using prototypal inheritance so I am not really sure when to use this pattern or it is even useful in JS.