Variable is a piece of memory that has a name and a value.

let age = 23

Here we have a variable age, that stores the numeric value 23.

Printing messages alongwith a variable:

We can also pass some message with values as well, for example.:

let age = 23
console.log('My age is: ', age)

You can see from the above example that we displayed a message My age is: 23 with a value of the variable age.

Why should we use the variables?

Variable can store any value, so you can assign it and use it as many times as you need. For example, if you need value 23 ten times, you can create and use a variable age with this value. Then, if you need to change your age, you`ll do it once by changing the variable, not changing all 10 occurrences of your value.

Compare two next examples:

console.log('My age is: 23')
console.log('My age is still: 23')
console.log('Now my age is: 23')

let age = 23
console.log('My age is: ', age)
console.log('My age is still: ', age)
console.log('Now my age is: ', age)

If you need to change your age, in the first example, you'll have to do it three times, and in the second, you'll only change the value of age variable, and then all other occurrences will be changed automatically. That's why we should use the variables.

Note: Always remember to separate the message and the variable with a comma (,) otherwise it will give error and you won't see your desired output.