**`mkdir()`** is a built-in function in PHP.

The `mkdir()` function creates a new directory within the specified path with a specified mode that sets permissions for the directory.

# Syntax
The following is the function prototype:

```php
 mkdir(path, mode, recursive, context) 
```

# Parameters and return value

The `mkdir()` function takes the following input parameters:

- `path`: The path of the file that is created.

- `mode`: Optional. A sequence of four numbers that specifies the permissions for the file. A breakdown of the four numbers is given below:

1. The *first* number is always `0`.
2. The *second* number specifies owner permissions.
3. The *third* number specifies the owner's user group permissions.
4. The *fourth* number specifies permissions for others.

The table below shows possible values for each number:

align-center

>**Note**: To set multiple permissions, we can add the above numbers. For example, `7` (`1` + `2` + `4`) specifies all permissions. The default `mode` is set to `0777`.

- `recursive`: Optional. Used to set recursive mode. 

- `context`: Optional. Specifies the #key# context: behavior of the stream #key# of the filehandle.

The function returns `TRUE` on successful execution. Otherwise, the function returns `FALSE`.

# Code

<?php 

// Creating a simple directory. Default mode is 0777
echo mkdir("./Edpresso");

echo "\n";

// Creating directory in recursive mode with different permissions
echo mkdir ("./Edpresso/myDirectory", 0700, true);

?>

In the above example, we start by creating a new directory, `Edpresso`. An output of `1` shows that the function was executed successfully.

Then, we create a new directory within our first directory with the path `./Edpresso/myDirectory`. This directory is created in recursive mode.

What is the mkdir() function in PHP?

mkdir() is a built-in function in PHP. The mkdir() function creates a new directory within the specified path with a specified mode that sets permissions for the directory. 

Value	Description
1	Execute permissions
2	Write permissions
4	Read permissions