Type inference

     Type inference is a feature in Swift that allows the compiler to automatically deduce the data type of a variable or constant based on the initial value assigned to it. This means that you don't have to explicitly declare the data type of a variable or constant, as the compiler can infer it for you. 

For example, if you assign a value of 95 to a variable like this:

var myNumber = 95

The Swift compiler will automatically infer that myNumber is an integer type (Int), based on the initial value of 95. 

Similarly, if you assign a value of "Hello, world!" to a constant like this:

let greeting = "Hello, world!"

The Swift compiler will infer that greeting is a string type (String), based on the initial value of "Hello, world!".

 Type inference can make your code shorter and more expressive, as you don't have to write out the data type for every variable or constant you declare. However, it's important to note that you can still explicitly declare the data type of a variable or constant in Swift if you need to, using the : syntax.