Create a SharePoint Group using PowerShell

Add-PSSnapin Microsoft.SharePoint.PowerShell –ErrorAction SilentlyContinue

#Custom Function to Create new SharePoint Group
function Create-SPGroup
{  
    param ($SiteURL, $GroupName, $PermissionLevel, $GroupDescription)  

    try
    {
        #Get the Web
        $web = Get-SPWeb -Identity $SiteURL

        if($web -ne $null)
        {
            #Check if Group Exists already
            if ($web.SiteGroups[$GroupName] -ne $null)  
            {  
                write-Host "Group $GroupName exists Already!" -ForegroundColor Red 
            }  
            else  
            {  
                #Create SharePoint Group
                $Web.SiteGroups.Add($GroupName, $web.Site.Owner, $web.Site.Owner, $GroupDescription)  
                #Get the newly created group and assign permission to it
                $Group = $web.SiteGroups[$groupName]  
                $roleAssignment = new-object Microsoft.SharePoint.SPRoleAssignment($group)  
                $roleDefinition = $web.Site.RootWeb.RoleDefinitions[$permissionLevel]  
                $roleAssignment.RoleDefinitionBindings.Add($roleDefinition)  
                $web.RoleAssignments.Add($roleAssignment)  
                $web.Update()  

                write-Host "Group: $GroupName created successfully!" -ForegroundColor Green
            }  

            $web.Dispose() 
        }
    }
    catch [System.Exception]
    {
        write-host $_.Exception.ToString() -ForegroundColor Red 
    }
}

#Call the function to create Sharepoint group
Create-SPGroup "http://sales.crescent.com" "Sales Managers" "Edit" "Group for Sales Managers"