Glossary/C-block

176.185. Each website on the Web is actually an IP address and the domain name (like example.com) routes your computer to that IP address.

Hosting providers buy large blocks of IPs, so if you have a lot of websites hosted by the same provider they may be in the same c-block.

One tactic that some people have used is buying many domain names and making websites that all link to a target website that they're trying to boost the SEO and search rankings for.

Search engines have caught on to this tactic and they're leary of websites that have lots of inbound links from websites all in the same c-block of IP addresses - it is considered black hat SEO.