With a type alias, you can provide an alternative name for an existing type since Kotlin 1.1:
For example, String Builder is an Alias in Kotlin
What does that mean is if we went to the declaration of a StringBuilder in Kotlin it will look like this,

which means that Kotlin itself doesn’t have a string builder class, it is just using a shortcode that refers to Java’s StringBuilder.
Now if we wanted to create a type alias our self, we declare it like this outside of the main function,
typealias StudentSet= Set<Student>
what this means is that whenever I type StudentSet in my code, the compiler will understand that I used a shortcode and what I meant was Set<Student>
Like this
val Students : StudentSet
It is just to save some time you know, that is why Kotlin exists already 😀