Every 4 years, World Sailing updates the Racing Rules of Sailing (RRS). 2017 marks the beginning of the next 4 year rules period. For the past 8 years, the changes to the rules have been mostly to simplify certain rules and make it easier to apply them on the water in real-time. For the 2017-2020 revision, not much has changed, but it's still worth knowing them. Over the next few months we'll discuss some of the changes here, but the study version from World Sailing is available right here. As an FYI, the 2017 New Years Race will be conducted under the existing rules.
For a list of the major changes, check out this piece by Dave Perry.