Western Digital is now shipping a 1 TB 2.5" hard disk.
A terabyte is now about the size of a deck of playing cards and can be powered by your laptop's USB port.
In about 1990, I participated in a Usenet (remember that?) "group buy" of 1 GB SCSI hard disks. That disk was a 5.25" "full height" form factor - that is, it fit in the same amount of space as two DVD-ROM drives stacked on top of each other.
It hasn't even been 20 years and now you can fit as much data as 1000 of those drives into about a tenth of the space, having paid about a fifth of the price for the privilege.