How do you use another IP address?

How many people can use a given dynamic IP address?

• This may come off very noobish, I don't know all that much about IP's, but I noticed that my ISP has given me a dynamic IP address and that my IP changes from time to time. I was wondering, if my IP has changed since last week, is anyone else using the old address from last week? Is it possible that someone in my town with the same internet provider can have the old address or do I have a set selection of addresses that rotate only for me? I hope I'm making sense....

• Answer:

  Yes, dynamic IPs are issued as needed. Your old IP is most likely in use by a different customer in your area. This approach was more useful when people were not connected to the internet 24/7 as one ISP could have say 100 IPs but 200 customers since not all customers were connected all the time. The pool of IPs you get rotated through is not specific to you but rather to your area and ISP. And every once in a while your ISP my change the pool they use for a certain area as they need to reshuffle IPs to deal with changes in network or number of customers.