UUIDs (Universally Unique Identifiers) are everywhere — database primary keys, request IDs, session tokens, file names. Most developers reach for UUID v4 by default, but UUID v7 is newer and better for many use cases. Here's what's changed and how to choose. What makes a UUID unique A UUID is 128 bits presented in a standardised format: xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx . The M character indicates the version (1–8), N indicates the variant. The guarantee: the probability of generating a duplicate UUID v4 is astronomically low. With 122 random bits, you'd need to generate about 2.7 quintillion UUIDs before having a 50% chance of a collision. For practical purposes, they're unique.…