I downloaded a setup of Ubuntu 12.04 LTS of about 600 MB (don't remember the actual size) and burned it on a USB using unetbootin. So, is that Ubuntu the offline installer? I can't run an online installer as I have a Broadband with a speed of 256 kbps. 
Would my downloaded Ubuntu, require an Internet Conncetion?
ubuntu;usb;live usb;iso
This is a standalone installer that you plug into your USB port and then boot your computer from the USB drive. It contains all of the basic stuff to install a complete, working Ubuntu system.According to the installation instructions on the website, they recommend you stay connected to the Internet so you can receive updates as you're installing. This ensures that your system will be up to date after installing. However, it isn't required.Once fully installed, you'll still need to connect to the Internet and update all of the packages, and you'll need to do this frequently in order to continue to keep the software up to date.