When the intended type should be explicit, write the type after a colon.

Declare the type you want

type_annotations.swift
let width: Int = 
let height: Int = 3
let title: String = "panel"
let area: Int = width * height
let summary: String = "\(title): \(area)"

print(summary)
let width: Int = 
let height: Int = 3
let title: String = "panel"
let area: Int = width * height
let summary: String = "\(title): \(area)"

print(summary)
let width: Int = 
let height: Int = 3
let title: String = "panel"
let area: Int = width * height
let summary: String = "\(title): \(area)"

print(summary)
annotation `let name: Type = value` tells Swift the exact type expected for the value.