You got `"double"` as an output in the last chapter, despite the number `10` being an integer. Let's investigate it.

What types can numeric values in R be? Let's remind. These are:
- `numeric`/`double` - real numbers.
- `integer` - integer numbers.
- `complex` - complex numbers.

But in the last chapter, you got `"double"` for an integer number. How to make R recognize integer numbers? One of the ways is to simply put `L` at the end of the number. For example,

typeof(10) # Example of double type
typeof(10L) # Example of integer type

This script will return the next output:
```
[1] "double"
[1] "integer"
```
Why do we even need to differentiate `10` and `10L` values? The answer is memory consumption - storing integers is 'easier' for computer memory.

In the first section, you will consider the very basics of R - outputting and performing basic operations. You will finish the section with the variables theory.

In the second section, you will learn the vector class in R, which represents single values too. You will consider the main data types for single values and how to work with multiple values of a kind at once.

Factors (or categorical variables) are widely used in real life. These are blood types, currencies, nationalities, brands, etc. Unlike numerical variables, factors are limited to a finite number of values.