A const, short for constant, is a variable that is not expected to change in value over the course of the program. They're useful for enforcing values that you don't want to change. Prior to the sixth edition of ECMAScript, ES2015 (often called ES6), it was possible to mutate the value of any variable, so mistakes such as using an assignment operator (=) instead of a comparison operator (== or ===) were common:
const firstName = "Jean-Luc"
const lastName = "Picard"
Sure, Captain Picard could change his name, but that doesn't seem very likely.
Sometimes, we want to declare a variable as a hard constant, such as pi or an API key. These use cases are, in general, the only exception to the naming standards, in that they are often all uppercase and sometimes have underscores:
const PI = 3.14159
const API_KEY = 'cnview8773jass'
So far, we have examples of two data types: strings and numbers. JavaScript doesn't have a concept of float...
