In our previous video, you pondered the question of why some apps are better than others. Here's another reason, interactivity. Users want to interact with apps that can understand and remember what they want to do. Interactive apps create a great user experience. That's why you need to be able to manage user inputs effectively. With Swift, you can store data temporarily using variables. The data stored as variables can be changed and reused depending on the condition or on information passed across the application. To declare a variable in Swift, you can use the keyword var. Let's unpack the syntax. Var implies that you are creating a variable. Next is an identifier called variable name, followed by an equal sign, and finally, the value which is stored in the variable. Swift provides a set of built-in variable types that represent numbers, such as integer or int for short and string. The integer datatype holds numbers while a string is a collection of characters. In this example, total count is an integer variable and has a value of 25. In this example, country is a string variable. But what do you do if you, for example, do not know the country? Fortunately, you can declare a variable without assigning a value right away. However, this is only possible when you specify the variable type. Let's declare a variable with an identifier called color, and set the datatype a string, because Swift now knows what type of variable it will be, you are allowed to assign the value of color only in the next line. Now let's focus on type annotation when declaring a variable. When you declare a variable without including the datatype such as integer or a string, Swift automatically does that for you using the datatype of the initial value. When you declare a variable as a string, Swift forces you to only assign content that matches the data type specified. For instance, say the variable country was created using string datatype, and a value of United States was assigned to it. If you try to assign an integer value of four in the next line, Swift will generate an error. Lastly, let's focus on how to display variables on screen. To perform special tasks such as displaying a variable, programming languages use something called functions. In Swift, to display a variable onscreen, you use a print function. To write a print function, you type print followed by a set of parentheses. You then add the value that you want to display on screen in between the parentheses. Let's explore a few examples of print functions. In this example, the variable first name has the value of Michael. If you include the word hello between quotation marks and first name in the print line function, then hello Michael will display on screen. Now let's include two additional variables, last name for surnames and full name to combine the first name and last name. Notice that a plus sign can be used to combine the values of two string values as a single string. The print function now displays the first name and the last name on screen. In this video, you were introduced to the var keyword, which you can use to declare variables. You also learned about different types of variables and how you can display them using the print function.