From my very first lines of C++ code circa Intro to Computer Science I, I've been in love with the concept of NULL, aka null, nil, undefined, or simply None (thanks, Python). It's a keyword that varies across programming languages in both syntax and technical meaning, but the fundamental idea is always that whatever is to be denoted by null has no value. It is not even 0, but it is also certainly not less than 0 because a negative number is something, even if it's the negation of a positive something.
Something that has no value is often very different than 0. 0 is, after all, something, and mathematicians and philosophers have been trying to suss that fact out since the ancient Greeks. In their wisdom and need to store data in named variables, computer scientists saw quickly enough that, yes, 0 is indeed something (32 bits of something, usually) and that is very different than representing nothing. Enter null.
In the short video above, MinuteEarth explains null by taking us to Null Island, a non-place located at 0°N 0°E, where the Prime Meridian hits the equator. There is no island here, though Null Island found within mapping systems as a trap to catch errors. Incidentally, Google Maps directs my search for "null island" to the Library of Congress—which is maybe even more amazing.