Public IP Addresses (also known as Static IP Addresses) are IP addresses that are visible to the public.Because these ip addresses are public, they allow other people to know about and access your computer, like a Web server.Public Ip is the IP which is visible in WAN means which goes out as a representative of our computer In some cases, you do not want people to access your computer or you want to restrict certain individuals from accessing your computer or server. A public IP address makes your equipment accessible to everyone on the internet and is needed for VoIP or if you want to give others to access to specific equipment on your network. You must therefore be careful to protect your equipment from hackers and viruses and not to allow your equipment to be hi-jacked and used as an open email-relay, for example.
These addresses can be used on a private network, but they’re not routable through the public Internet. This not only creates a measure of much-needed security, but it also conveniently saves valuable IP address space.
private ips are the ips which we use within a company or organisation. A private IP address is for private use within the network and allows many more PCs to be connected. If a customer is using a private IP and later wants VOIP they would need to change to a public IP address.