The Get-ChildItem command without any options will list the files and directories in the present working directory.

> Get-ChildItem

    Directory: C:\Users\john.doe

Mode                LastWriteTime         Length Name                                                                                                                    
----                -------------         ------ ----    
d-----        3/26/2021   4:02 AM                my-directory                                                                                                                                                                                                                                                                                                                                          
-a----        8/1/2022   11:37 PM             11 example.txt

The -recurse flag can be used to list the files and directories below the present working directory.

> Get-ChildItem -recurse

The -path option can be used to specify the base directory to search from.

> Get-ChildItem -path 'C:\temp' -recurse

The -filter option can be used to only return files and directories that match the filter.

> Get-ChildItem -path 'C:\temp' -recurse -filter '*.txt'

The Format-Table filter can be used to just return the file names.

> Get-ChildItem | Format-Table Name -HideTableHeaders
my-directory                                                                                                                                                                                                                                                                                                                                          
example.txt

Here is how you could loop over each file.

$files = Get-ChildItem -file

foreach ($file in $files) {
    Write-Output $file.FullName
}

Sometimes, permission denied will be returned at certain sub directories. The -erroraction silentlycontinue option can be used to ignore such errors.

> Get-ChildItem -recurse -erroraction silentlycontinue

The -file flag can be used to only display files.

> Get-ChildItem -file