What is a Dedicated IP Address
Each computer connected to the Internet is identified by a unique number so other hosts on the Internet can find it and direct data to/from it.
Because the initial pool of IP addresses were estimated at around 4.4 billion during it's introduction in 1983, IP addresses were handed out to large corporations and research institutions upon request with little or no restriction. In the mid-90s, with the exploding popularity of the world wide web and the mass-market introduction of the Internet, IP address space began to be assigned out at a much higher rate. Realizing that the IP address space would eventually run out, there were several methods of extending the life of the IP address space while engineers worked on a new mechanism for identifying computers on the Internet.
One of these methods was the introduction of "shared" hosting, where several web sites and domains could be hosted on one web server. This allowed multiple sites to use the same IP address and connection. For examples, if 50 websites could be identified by one IP address, then that leave 49 potential IP addresses to be used for 50 more websites each, meaning that a company can use 2500 websites with only 50 IP addresses.
However, in some cases, there might be a need for a site to be identified by an IP address that is not shared with other sites on that server. In a shared hosting services, this is usually called a Dedicated IP Address.
Why Do I Need a Dedicated IP Address?
Short answer: You don't, unless you have a high volume traffic site or just want to use one.
Longer answer: A dedicated IP address doesn't do anything for your web site other than uniquely identify it in the IPv4 address space.
Dedicated IP addresses are assigned to customers who plan on using SSL certificates on their behavioral targeting sites. We must keep track of these since our network provider will need justification of each block of IP addresses they assign to us.
There are some other circumstances that an IP address might be necessary, but you'll need to submit a ticket to support to verify whether your circumstance is necessary.
Some reasons why you don't need a dedicated IP:
Search Engine Optimization (SEO)
To work with older browsers (Older operating systems don't support SNI, otherwise known as Server Name identification. Until recently, the one common reason for having a unique, or dedicated IP address, was that you could only use SSL encryption on a dedicated IP address. That has since changed, with the implementation of SNI in cPanel. With SNI you can install an SSL certificate on an account that's using a shared IP address OR a dedicated IP address.)
To make the website run faster