In JavaScript, it's best practice to declare variables before using them. This declaration can happen at the time of assignment to a value, or you can define a variable without a value.
Unlike some other languages, JavaScript is loosely typed, so you don't need to declare what type of variable you're creating. By convention, variables in JavaScript start with a lowercase letter and follow camel-casing, rather than snake-casing. So, myAge is preferable to my_age or MyAge. Variables cannot start with a number.
There are three keywords used to declare variables in JavaScript: const, let, and var.
