Items Stories, comments, jobs, Ask HNs and even polls are just items.
Items Stories, comments, jobs, Ask HNs and even polls are just items. They're identified by their ids, which are unique integers, and live under https://hacker-news.firebaseio.com/v0/item/.
Top Stories The current top 100 stories are at https://hacker-news.firebaseio.com/v0/topstories.
Top Stories (Actual Items)
Users Users are identified by case-sensitive ids, and live under https://hacker-news.firebaseio.com/v0/user/.