SharePoint Online Taxonomy - Output Terms up to 6 level with PowerShell and CSOM

As you know, SharePoint taxonomy refers to a catalog of objects in your SharePoint environment or the process of categorizing or classifying objects based on a taxonomic scheme.

The taxonomy is structured like below:
  The Termstore -
         Groups
             Termset
                        Term ( level 0 )
                               Term ( level 1)
                                     Term ....

The structure could be deeper as you need, but a very deep structure will not help you to keep real structured information on your tenant.  (It is recommended maximum 3-4 level  deep for terms.)

If you run it on a machine without SharePoint installed on it, you will need 2 DLLs: Microsoft.SharePoint.Client.dll and Microsoft.SharePoint.Client.Taxonomy.dll (you can copy them from SharePoint server).

The script in PowerShell using CSOM proposed is this one:

---

$url=Read-host "Introduce your tenant's URL"
$cred =  Get-Credential
Add-Type -Path "\\path\Microsoft.SharePoint.Client.dll" 
Add-Type -Path "\\path\Microsoft.SharePoint.Client.Taxonomy.dll"
 
$clientContext = New-Object Microsoft.SharePoint.Client.ClientContext($url)
$credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($cred.username, $cred.Password)  
$clientContext.Credentials = $credentials 
 
############# Get your tenant Taxonomy details ##################
$MMS = [Microsoft.SharePoint.Client.Taxonomy.TaxonomySession]::GetTaxonomySession($clientcontext)
$clientContext.Load($MMS)
$clientContext.ExecuteQuery()
$TermStores = $MMS.TermStores
$clientContext.Load($TermStores)
$clientContext.ExecuteQuery()
 
#Bind to Term Store
$TermStore = $TermStores[0]
Write-Host "#################################      Taxonomy on tenant which contain the Site collection   #################################"
Write-Host "#################################      $url    #################################"
$clientContext.Load($TermStore)
$clientContext.ExecuteQuery()
""
$Groups = $TermStore.Groups
$clientContext.Load($groups)
$clientContext.ExecuteQuery()
 
for ($i = 0; $i -lt $Groups.Count; $i++)
{ 
write-host "For the Group: "$groups[$i].Name " / " $groups[$i].id
 
$groupname =$groups[$i]
$termsets = $groupname.TermSets
$clientContext.Load($termsets)
$clientContext.ExecuteQuery()
    foreach ($termset in $termsets ){
    write-host "  The TermSet:"$termset.Name " / " $termset.id  -ForegroundColor DarkYellow
 
$terms = $termset.Terms
$clientContext.Load($terms)
$clientContext.ExecuteQuery()
foreach ($term in $terms ){
write-host  "    The Term ( level 0): "$term.Name  " / " $term.id  -ForegroundColor Gray
 
$items = $term.Terms
$clientContext.Load($Items)
$clientContext.ExecuteQuery()
 
foreach ( $term_level1 in $items ){
Write-Host "      Level 1:" $term_level1.Name " / "$term_level1.ID -ForegroundColor cyan
#$term_level1.TermsCount
 
    $items2 = $term_level1.Terms
    $clientContext.Load($Items2)
    $clientContext.ExecuteQuery()
    foreach ( $term_level2 in $items2 ){
   # $term_level2.TermsCount
    Write-Host "        Level 2:" $term_level2.Name " / "$term_level2.ID -ForegroundColor green
 
        $items3 = $term_level2.Terms
        $clientContext.Load($Items3)
        $clientContext.ExecuteQuery()
        foreach ( $term_level3 in $items3 ){
        #$term_level3.TermsCount
        Write-Host "            Level 3:" $term_level3.Name " / "$term_level3.ID -ForegroundColor yellow
             
            $items4 = $term_level3.Terms
            $clientContext.Load($Items4)
            $clientContext.ExecuteQuery()
            foreach ( $term_level4 in $items4 ){
            #$term_level4.TermsCount
            Write-Host "              Level 4:" $term_level4.Name " / "$term_level4.ID -ForegroundColor blue
 
                $items5 = $term_level4.Terms
                $clientContext.Load($Items5)
                $clientContext.ExecuteQuery()
                foreach ( $term_level5 in $items5 ){
                #$term_level5.TermsCount
                Write-Host "                Level 5:" $term_level5.Name" / "$term_level5.ID -ForegroundColor red
                } 
            }  
        }
    }
}
}
}
}

The results, deeper up to 6 levels like below. Different colors for each level and it's present in the GUID, which is useful. If you need to populate a managed metadata field in a list/library using PowerShell and CSOM on Sharepoint Online.