The 2020 primary season is well underway, and Democratic veterans and newcomers alike are lining up to challenge President Donald Trump. Sens. Bernie Sanders, Elizabeth Warren, and Kamala Harris have entered the fray. South Bend, Indiana, Mayor Pete Buttigieg has emerged as a surprising standout. Former Vice President Joe Biden announced his candidacy after months of speculation.

With the field more crowded than it’s been in years, it can be easy to get lost in the horse race — and hard to keep track of where candidates stand on the issues that affect people’s lives. Where are there real, meaningful differences between competitors? Who supports Medicare-for-all? Who would do the most to alleviate poverty in America?

Here, you’ll find everything you need to know about the policy debates that will define the 2020 primary — from health care to climate change to criminal justice. While the Iowa caucuses are still months away, this guide will get you up to speed. We’ll update it as Vox continues to cover candidates’ policy proposals throughout the campaign.