what and how much is 1 gigabyte?

1 gig is a lot of space.

to give you an idea;

x amount of movies at 'this' size

x amount of images at 'this' size

now compare that to actual data - even a large
website with lots of pictures would only use x
amount of data, leaving plenty of extra space
for storage, or whatever you might want to use
it for.

possible uses:

backups of your phone data