The haxe compiler uses type inference to infer (deduce) the type from values you assign to a variable.
This relieves you from the burden to strongly type all your variables without losing strong typing.

For example, the following code:

var f = 10.5;
var s = "foo";
var arr = ["hello", "world"];

will be compiled as if you had written:

var f:Float = 10.5;
var s:String = "foo";
var arr:Array<String> = ["hello", "world"];

(Mostly) for debugging purposes, you can check at compile time which type the compiler deduced, by using the special identifier '$type'.
We'll use it in the rest of this explanation to show how the compiler infers types.