The IP address

• An IP address is used to recognize a computer connected to the Internet. Such an address is similar to a telephone number.
• What can someone do with your IP address? This is not your home address, but it can reveal the city you live in. www.mijn-ip.net
• In an email, sometimes an IP address can be found https://www.eenmanierom.nl/ip-adres/  (This link explains how to look for that in the various email programs). If you use Proton email you can at least be sure that doesn't happen. Gmail doesn't either, by the way.
• If you have an unknown stalker you can reverse engineer a trap. http://www.mijn-ip.net/ip-adres-achterhalen/
• With a VPN, you can change your own IP address to a different number that also doesn't reveal the place where you live.