There are two ways of creating variables in Scala.

The preferred way is by creating a constant using the key word val.

This way of creating a variable supports the second idea of functional programming,

as the contents of a val cannot be changed.

Additionally, you can create a mutable variable in Scala

by using the key word var whose contents can be changed.

Let's see how this works in the REPL, the interactive shell, which we can get to by

opening up a terminal in a Mac or command prompt in Windows and typing Scala.

Let's open up the terminal to start the Scala REPL.

REPL stands for read, evaluate, print, and loop, and

it's very useful in evaluating expressions.

Here, we've created a variable name greeting.

A constant whose values cannot be changed.

Attempting to reassign the value of variable greeting

will throw a reassignment to val error.

Let's take a look at that.

Let's take a similar approach, but with a mutable variable this time.

We've created a variable called message, which contains the string, hello world.

Because vars are mutable, we can reassign its value.

In both instances, you may have noticed two things.

First, we aren't required to provide a semicolon at the end of the statement, and

that's because Scala supports semicolon inference.

Second, we didn't have to specify the parameter type.

That's because scala has a built in type inference mechanism

which allows it to figure out what the type of variable should be.

Although not recommended, we can always supply the semicolon or

the type information if we really wanted to.

Let's take a look.

Awesome, we learn how to create values and variables in Scala.

In the next video, we will create our first Scala app and learn about functions.

See you there!