I’ve been doing some work with UUIDs lately, and I got to thinking: what are the chances of repetition?

Quick background note: Universally unique identifiers or UUIDs are a common tool for giving a unique identity to a piece of data. Think of them as serial numbers for information.

Apparently the chances of repeating a UUID are so small that the chance is not even be considered a risk. The spec says “A UUID is 128 bits long, and can guarantee uniqueness across space and time.”

Wikipedia states that the total number of UUIDs is in the range of 10^36 or 1000000000000000000000000000000000000 source

According to that same Wikipedia page, this number is greater than number of bacterial cells on Earth and the number of atoms in the human body.