In short, a «value» or «secret» is a long and unique string of numbers that is practically impossible to guess, even for a computer with infinite tries. (bitcoinmagazine.com)
SciAm reviews The Complete Idiot's Guide to String Theory and Human: The Science behind What Makes Us Unique (scientificamerican.com)
At birth, every person is assigned a unique string of 11 digits, a digital identifier that from then on is key to operating almost every aspect of that person's life — the 21st - century version of a Social Security number. (fortune.com)