Save the below script in a .ps1 file (powershell script file).
Import-Module WebAdministration
dir IIS:\Sites # Lists all sites
dir IIS:\AppPools # Lists all app pools and applications
# List all sites, applications and appPools
dir IIS:\Sites | ForEach-Object {
# Web site name
$_.Name
# Site's app pool
$_.applicationPool
# Any web applications on the site + their app pools
Get-WebApplication -Site $_.Name
}