It's really simple. The first number increments when a new release branch is cut off master, about every 6 weeks. The second is always zero. The third is a buil

It's really simple. The first number increments when a new release branch is cut off master, about every 6 weeks. The second is always zero. The third is a build number, which is an incrementing global. There were exceptions in the early days when the team was still figuring things out. For example, release-branches were cut more sporadically, and the middle number was used to sorta-kinda represent smaller feature changes. You might be thinking of release dates tied to a set of completed product features. Chrome doesn't work that way. The team ships on a regular schedule, holding back features that aren't ready for the public. Frequent releases help mitigate the urge for individual teams to ship low-quality stuff just because the next release train was a long and/or unpredictable time in the future.