There are two ways of creating variables in Scala. 0:00 The preferred way is by creating a constant using the key word val. 0:03 This way of creating a variable supports the second idea of functional programming, 0:07 as the contents of a val cannot be changed. 0:12 Additionally, you can create a mutable variable in Scala 0:15 by using the key word var whose contents can be changed. 0:19 Let's see how this works in the REPL, the interactive shell, which we can get to by 0:23 opening up a terminal in a Mac or command prompt in Windows and typing Scala. 0:27 Let's open up the terminal to start the Scala REPL. 0:33 REPL stands for read, evaluate, print, and loop, and 0:37 it's very useful in evaluating expressions. 0:41 Here, we've created a variable name greeting. 0:53 A constant whose values cannot be changed. 0:55 Attempting to reassign the value of variable greeting 0:58 will throw a reassignment to val error. 1:02 Let's take a look at that. 1:05 Let's take a similar approach, but with a mutable variable this time. 1:10 We've created a variable called message, which contains the string, hello world. 1:19 Because vars are mutable, we can reassign its value. 1:24 In both instances, you may have noticed two things. 1:33 First, we aren't required to provide a semicolon at the end of the statement, and 1:37 that's because Scala supports semicolon inference. 1:41 Second, we didn't have to specify the parameter type. 1:45 That's because scala has a built in type inference mechanism 1:49 which allows it to figure out what the type of variable should be. 1:53 Although not recommended, we can always supply the semicolon or 1:57 the type information if we really wanted to. 2:01 Let's take a look. 2:04 Awesome, we learn how to create values and variables in Scala. 2:12 In the next video, we will create our first Scala app and learn about functions. 2:16 See you there! 2:21