Each variable has its unique name - **identifier**. There are some rules for naming variables:


- Names must start with a letter or underscore _ and contain only letters, digits, and underscores (no special characters or whitespaces). 
- Names can be different because of the case (myDog and MyDog are two different variables). 
- Reserved words such as `int` cannot be identifiers.

There are short names for variables such as `x` and `y`, and also descriptive names like `monthIncome` or `amountPerYear`. The good rule is to use descriptive names since it makes your code more clear and understandable.

In cases, you don’t want to define the type of the variable automatically by declaration you can use the `auto` keyword. It infers the type from the value of the variable, so it’s necessary to initialize the variable when you define it.

```
 auto x = 5; // int
 auto y = "Hello"; // string
```

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In this section, you will learn the most important things about variables manipulations.

In this section, you will learn how booleans can help in creating programs behaving differently depending on some conditions.

In this section, you will learn how to write different loops in C++ to manipulate your data!

In this section, you will learn how the array works and how to apply loops to iterate through the array.

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Identifiers

Define the variable automatically using the valid name of the variable: