Pokemon Go launched in a massive way but developers Niantic Games seemed to get so snowed under keeping the game afloat that they didn't have time to add new features.
As a result, players left by the thousands - mostly because there was bugger all to do. Months on from release and the developers are still trying to keep things going. Recently they gave some good incentives to play over Halloween with bonus candy and they're keeping that activity up with newly announced content.
Basically it's daily incentives to make you do things regularly along these lines:
Catching a Pokémon every day will earn the following bonus:
Catching a Pokémon every day for 7 days straight will earn the following larger bonus:
Visiting a PokéStop and spinning the Photo Disc every day will earn the following bonus:
A number of additional items
Visiting a PokéStop every day for 7 days straight will earn the following larger bonus:
A greater number of additional items
Now there's no clear idea of when this will actually start, which is something the company has been notoriously bad at. Will this be enough to keep people checking in? Probably not...