When you type an alphabetical address into your web, the address is turned into a numbered IP address formatted as ###.###.###.###. This IP address identifies a site on the internet. In addition, IP addresses identify Internet connections. In other words, when you connect to the Internet, the device you are connecting through (i.e. your home or work Internet) is identifiable via its IP address.
For websites, the IP address almost never changes. However, for many Internet access devices, the address is dynamic. From time to time, the Internet service provide will use a new address to identify the device, especially after a reboot. This change will cause a problem if you attempt to remotely access the device. For example, when you attempt to connect to your office from your home. How do you know what the new address is and how do you update the alpha address to match the numeric address?
In contrast, a static IP Address is for one customer on one IP address—it will never change. You can safely point an alphabetic address to the IP address because it does not change. This greatly simplifies remote access.
Most Internet Service Providers will sell you a static IP at an additional cost – often $10-$15 per month. However, if your provider does not offer this service or you don’t want to pay this extra money, there ways to get the same functionality. DynDNS is service that costs around $25 annually and does two things. First, it allows you to create a remote access hostname. Second, it assigns that to your Internet modem. So, instead of having to remember your IP address or try to figure out what dynamic address it currently is, you simply type the hostname and it resolves it to your current IP address. Your hostname never changes even if your dynamic IP does.