Pull to refresh makes a lot of sense where you have a vertically scrolling list with the most recent entries at the top. The user will discover it naturally as

Pull to refresh makes a lot of sense where you have a vertically scrolling list with the most recent entries at the top. The user will discover it naturally as they look for more entries past the current top one. However I've seen it used in different contexts (eg. a web browser) where it's less easy to defend.