Every computer connected to the internet has an IP address and this is normally allocated to your computer by your Internet Service Provider when you connect.
<<< Does my computer always have the same IP address? >>>
Generally, you will not have the same IP address, particularly with ADSL or Dialup access. Some ISPs offer the facility to have a "static" IP address, which doesn't change and which may be required particularly by businesses. This is normally more expensive. With Cable broadband, where the Cable Modem is permanently powered on, the IP address will normally only change if a different network adapter connects to it.
<<< Can anyone see my IP address? >>>
Yes because you couldn't do anything online if your IP address wasn't "visible". Everything you download, including accessing web pages, involves sending packets of data to your IP address.
<<< Can anyone trace my IP address to my home? >>>
No, it can be traced back to your ISP
To see what your IP address is click here