It marks new accounts (I think created in the last 14 days)

thank you! I guess I was already green :)

I was about to add a snarky "Easy answer: Read the HN F.A.Q. level comment but after a bit of looking around the answer isn't obvious (yet somehow I sort of knew it through being a HN user) and using the Search box didn't return anything useful so instead of snark I used a bit of google-fu & here's your answer. HTH.

https://news.ycombinator.com/item?id=2456602

https://news.ycombinator.com/item?id=3848762

TLDR; Green Accounts are for users who are under 5 days old. You can see all their submissions at - http://news.ycombinator.com/noobstories

[Edit to add, Or perhaps it is 14 days as per https://news.ycombinator.com/item?id=3848820]

Double Edit: Confirmed, 14 days (not 5). See https://github.com/minimaxir/hacker-news-undocumented for a full list

wow, you are very thorough and I would have gladly accepted the snark :) This was a case of efficiency on my part,i.e. 30second hacker-news comment vs 5-10 minutes searching (my wife might not call it efficiency). Thank you for the response!

New users have a green username. This is so you can provide friendly, helpful, notes to those users.

great thank you for the information!