|so you mean to say that the internet doesn't recognize my LAN (internal) IP of my comps??|
Not directly, but can be made to. Look up port forwarding and router functions
but responds to an external IP which is unique??
Yes, all external IP addresses are unique.
and do we have anything like External IP??
I don't know, do you? You must have to connect to the Internet,
Internal/external IP addresses are analogous to Private/Public IP addresses.
Look up both on Google. There a pages and pages of information, That's how I found out.