your IP address is not too different from your home address in that it's a way to find you. your ISP provides either a dynamic or static IP address. a dynamic address changes over time. a static address stays the same over time. most residential accounts will be dynamic. (business accounts want static for a number of reasons.) you'd think this is good in that your IP address will change but it actually doesn't change too often. with some ISPs you can leave your modem completely unplugged for anywhere from minutes to hours to days which will trigger you to receive a new IP address.
How long do ISPs keep track of your dynamic IPs? Not sure, to be honest.
Do this. Go to google and search for 'what is my ip'. You'll get an IP address in your result.
If you have an iphone you can download 'betternet vpn' which is free to use. MOST VPNs for your phone cost money. This app is free so don't be fooled when you first launch it and it attempts to get you to sign up for the paid version. Once installed, open it and click on the buttons to get connected.
Then go back to google and search for 'what is my ip'. If it worked, you'll get a different IP address.
If you have a PC download & install "open vpn." it's free. then go to vpnbook.com where there will be an area for 'openVPN' accounts. download a 'certificate bundle'. make note of the username and password at the bottom of the choices for you to download. make sure open vpn is running on your computer - it looks like a small monitor icon in the bottom right corner of a windows based machine. right click on the open vpn program and choose 'import file.' browse to your download area and double click the file you just downloaded from vpnbook. Once imported you can right click on 'openVPN', highlight one of the connections, and then click connect. (This all seems like a lot but trust me, it's not too bad.)
Now that the heavy lifting is complete - go back to google and search for 'what is my ip.' You'll get yet another IP address in your result.
Turn off the VPN from your computer or phone and google 'what is my IP' and you'll see the first IP you started with.
Lastly, you can download the "Tor" browser. It's free. (see a theme with my suggestions?

Tor is an 'internet browser' just like mozilla firefox, google chrome, and internet explorer. except it's designed to be very secure. once you download and install Tor that browser acts similar as a VPN. open Tor and search 'what is my ip'. You'll notice it uses duckduckgo.com instead of google. because unlike google, it doesn't track your searches. and yet again, you'll get a different IP address.
Lastly, you should change your IP address when making bitcoin transactions so that it's more difficult to trace. because bitcoin is NOT entirely anonymous.