When your site is hosted on a server it is given an IP address. This is the numerical address or location of the site that various servers and backbones around the globe use to help people find your site. When you are building a site determining if your site can share an IP or if it needs its own IP can be a big decision.

A shared IP is exactly what it sounds like. Your site is hosted on the same IP as many other sites. This can occur through the use of virtual hosting which often shares IP's across many sites or it can also happen when you run your own dedicated server and you choose to put multiple sites on the same IP.

A static IP is a single IP that is used for one site only. You can get static IP addresses with virtual hosting packages, but they are more common in dedicated servers. With a static IP only the site you assign to it actually uses it. One of the major benefits of a static IP is that when your site is indexed by search engines they will not see any other sites on that IP which might give your site a little boost in the search engine rankings because they will see it as a single quality site, not as part of a larger network.

When sharing an IP there are a few things that could potentially affect your site. The primary thing to worry about is spam. If you are on virtual hosting you have no control over what the other sites sharing your IP are doing. If one of them starts spamming their site or they get their site blacklisted, often times this can affect the entire IP. Getting an IP listed in Spam Haus could mean that people won’t get emails you send from your site because they are now blocked by the ISP. You did nothing wrong, but are now paying for other’s actions.

In the end the best advice a person can get is this: If you are running a small hobby style site, a shared IP on virtual hosting should work just fine. If you are running any kind of site for a business or an organization or even a large personal site, a static IP is probably the best way to go, or at least use a shared IP on a dedicated server you run so you know what other sites are sharing that IP.