If you have a domain name...

When you register a domain name your details are placed into a WHOIS database - this is to identify the owner (registrant) and admin, billing and technical contacts for the domain - the downside is that is this 'public'.

If you are an individual (rather than a business) some registries offer the option to 'opt-out' of having your details visible - well worth considering!

Some ISP's / registries also set themselves as the admin, billing and technical contacts - saving you the spam! But be careful that you make sure they have your current email address as if they cannot contact you you run the risk of your domain name being deactivated if you do not renew it with them.