There will be a timer on scrums and kicks in January to speed up the game.
The'shot clock' gives players 90 seconds to take a conversion and a minute to take a penalty.
Penalties will be given for timewasting and scrums have to be started within 30 seconds.
On January 1st, the rules come into effect.
There is a clock for kicks at goal.
The proposals were first reported by Chris Jones in November.
Phil Davies, World Rugby's director of rugby, said: "World Rugby will work with broadcasters and match hosts to implement on-screen shot clocks for penalties and conversions."
World Rugby hopes the changes will improve the flow of the game and reduce the reliance on television match official reviews.
When a try is scored, water carriers will only be allowed into the field.
In a game with no tries, a natural stop should be used.