But why did they need to create another ‘a class’ ?
Just seems a bit strange, if you already have ‘a class’ , what is the reason for not putting a simple ‘hover…’ in there? Why do you need another class altogether just for that?
Just a little vocabulary thing - you’re creating selectors.
Very often when you’re using CSS there will be overlap in your selectors. You want one rule that targets “all links” and applies a style to them. You also want a rule that finds “links that users are currently hovering over” and applies a different style. You could hypothetically also want to target “all links that are inside the navigation menu” and make them look different. And so on. All of those would include a as part of the selector.