What is Dynamic DNS domain??

[llegent]

Ok, could anyone help to tell me what actually is "Dynamic DNS domain"?? I just happen to notice of such thing today!:o
1. What could it actually do??
2. Is it some sort of free service??
3. How do I go about registering it?
4. Any regulation on using it?
5. How do I potentially MAKE MONEY from it??:p...if possible!

Any kind soul willing to offer guides??

[triumph]

There are free services that offer it. Not sure how you would make money with it.

Basically it lets you have a static domain name even if your server is at your house using a dynamic ip address.

Basically it works with a program on the server, or a computer on the network or in my case on my router. My router contacts the company with the dynamic DNS servering, and tells them what my ip address is when I log into my dsl. Then they set up their name servers to point my domain name to my ip address.