18 years ago, a fairly complete index of the entire Internet — circa 1995 — could fit on a single CD-ROM — about 20,000 sites, as the box for Microforum's Internet Connection '96 says. [Update: See comments below for a discussion on the number of websites in 1995 and 1996] I ran a website back then, and the Web did indeed feel that small. FTP sites were still a big deal in those days, so that number may include them as well.
Today, some estimates say that the Web alone consists of over one billion websites. Consider storing a simple list of one billion websites URLs. If each URL was about 25 characters long (I'm just making this up as an example), it would take around 25 gigabytes to store the list alone (or about 39 CDs worth). Google stores that list and copies of individual websites for caching. Needless to say, that takes quite a bit more storage room.
So it's amusing to think back to a time when you might actually buy a professionally mastered and duplicated CD-ROM containing web addresses, many of which were potentially obsolete by the time the disc landed in your hands (I just used Yahoo's web directory). Now we have Google. Imagine that: using the Internet to index itself.
Discussion Topic of the Week: What year did you create your first website?
See Also: Internet In a Box (RSOTW, 2014)