// gives you the length of an array/a slice
// It's a built-in function, not a attribute/method on the array.
len(a)

var a [10]int // declare an int array with length 10. Array length is part of the type!
a[3] = 42     // set elements
i := a[3]     // read elements

// declare and initialize
var a = [2]int{1, 2}
a := [2]int{1, 2}   //shorthand
a := [...]int{1, 2} // elipsis -> Compiler figures out array length