Most hosting plans give you one shared ip for free but you can purchase more if required.
Why would I want to have a dedicated or more than one IP address ?

Thanks in advance for any help.

a dedicated ip lets you have your own ssl certificate – eg https://yoursite.com – this is a must if you sell stuff from your website, eg take customer details, credit card info etc.

There are someconcepts listed here, as to reasons to have a dedicated IP.

2. SSL . Yes, you do need a dedicated Ip if you want your Own SSL certificate for your site, however, almost all hosts will let you use their shared SSL at no additional cost to you. Some charge a fee, but most don’t. You don’t need a dedicated IP if you use their shared SSL.

3. With a dedicated IP, you can upload your site and test scripts (cgi-programs) if you set things up with the sites IP, instead of the domain name.
You can still upload your site with a shared IP, but you must use a special link to view it until the name works, and you can’t test cgi scripts until the name works. Front page should not be used to upload a site until thename works in your browser. Front page hidden scripts and includes will be broken if you upload by IP instead of your domain name in most cases. This breaks menus and forms.

The shared IP can get black listed. However, this is generally due to spammers sending spam through the server. The servers main IP is generally the mail servers IP, and that is what gets banned. This would affect all sites on that machine even if they have their own dedicated IP, because it is the email servers IP that is listed in the headers, and that is what IP all the outgoing mail comes from. Dedicated or not, it will still affect you, and it is a hassle for the host to get cleared up in most cases.

you can also have dedicated IP’s for your custom nameservers. As long as your host sets it all up correctly, your clients won’t know that you’re a reseller.

A disadvantage perhaps is that you don’t normally get a free dedicated IP. So you spend a monthly fee for it.