#Load SharePoint CSOM Assemblies
Add-Type -Path "C:Program FilesCommon FilesMicrosoft SharedWeb Server Extensions16ISAPIMicrosoft.SharePoint.Client.dll"
Add-Type -Path "C:Program FilesCommon FilesMicrosoft SharedWeb Server Extensions16ISAPIMicrosoft.SharePoint.Client.Runtime.dll"
Add-Type -Path "C:Program FilesCommon FilesMicrosoft SharedWeb Server Extensions16ISAPIMicrosoft.SharePoint.Client.Taxonomy.dll"

#Variables for Processing

$AdminURL = "https://abc-admin.sharepoint.com/"
$TermGroupName= "Site Collection - abc.sharepoint.com-sites-123site"
$TermSetName="Due Diligence"
$CSVFile ="C:Usersdm123DownloadsTermStore.csv"
$TermHeaderInCSV ="Due Diligence"

Try {
    #Get Credentials to connect
    $Username = "123@abc.com"
    $Password ="LE$b1yuio$!."
    $Credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($Username, $Password)

    #Setup the context
    $Ctx = New-Object Microsoft.SharePoint.Client.ClientContext($AdminURL)
    $Ctx.Credentials = $Credentials

    #Get the term store
    $TaxonomySession=[Microsoft.SharePoint.Client.Taxonomy.TaxonomySession]::GetTaxonomySession($Ctx)
    $TaxonomySession.UpdateCache()
    $TermStore =$TaxonomySession.GetDefaultSiteCollectionTermStore()
    $Ctx.Load($TaxonomySession)
    $Ctx.Load($TermStore)
    $Ctx.ExecuteQuery()

    #Get Termstore data from CSV and iterate through each row
    Import-Csv $CSVFile | ForEach-Object {

        #Get the Term Group
        $TermGroup=$TermStore.Groups.GetByName($TermGroupName)

        #Get the term set
        $TermSet = $TermGroup.TermSets.GetByName($TermSetName)

        #CSV File Header Row in Term to Add
        $TermName = $_.$($TermHeaderInCSV)

        #Check if the given term exists already
        $Terms = $TermSet.Terms
        $Ctx.Load($Terms)
        $Ctx.ExecuteQuery()
        $Term = $Terms | Where-Object {$_.Name -eq $TermName}

        If(-not $Term)
        {
            #Create Term Set
            Write-host "Creating Term '$TermName'" -ForegroundColor Cyan
            $Term = $TermSet.CreateTerm($TermName,1033,[System.Guid]::NewGuid().toString())
            $Ctx.Load($Term)
            $Ctx.ExecuteQuery()
            $Term.TermStore.CommitAll()
            $TaxonomySession.UpdateCache()
            Write-host "New Term '$TermName' Added Successfully!" -ForegroundColor Green
        }
        else
        {
            Write-host "Term '$TermName' Exists Already!" -ForegroundColor Yellow
        }
    }
 }
Catch {
    write-host -f Red "Error Importing Term store Data!" $_.Exception.Message
}