To install Debian on a machine without an Internet connection, it's possible to use CD images (650 MB each) or DVD images (4.4 GB each). Download the first CD or DVD image file, write it using a CD/DVD recorder, and then reboot from that.
The first CD/DVD disk contains all the files necessary to install a standard Debian system.
To avoid needless downloads, please do not download other CD or DVD image files unless you know that you need packages on them.
The following links point to image files which are up to 650 MB in size, making them suitable for writing to normal CD-R(W) media: