An FTP install is a means of installing an operating system using the ftp protocol instead of forcing the person doing the install to have the complete package on hand. Most distros allow this type of install, and will only require a single boot floppy to bootstrap the installation.
Some advantages to this installation method are:
- Having access to the latest system binaries (if you choose to run a development or -current version of the OS
- Only download the software you need (not a whole CD worth of stuff you don't want)
- Install an entire OS using a single floppy disk
The obvious drawback is that installation will take a long time on a slow connection.